style(core/apps): use new syntax for typing

core/src/apps/base.py

@@ -139,9 +139,9 @@ async def handle_Ping(ctx: wire.Context, msg: Ping) -> Success:
 async def handle_DoPreauthorized(
     ctx: wire.Context, msg: DoPreauthorized
 ) -> protobuf.MessageType:
-    authorization = storage.cache.get(
+    authorization: Authorization = storage.cache.get(
         storage.cache.APP_BASE_AUTHORIZATION
-    )  # type: Authorization
+    )
     if not authorization:
         raise wire.ProcessError("No preauthorized operation")
 
@@ -157,9 +157,7 @@ async def handle_DoPreauthorized(
 
 
 def set_authorization(authorization: Authorization) -> None:
-    previous = storage.cache.get(
-        storage.cache.APP_BASE_AUTHORIZATION
-    )  # type: Authorization
+    previous: Authorization = storage.cache.get(storage.cache.APP_BASE_AUTHORIZATION)
     if previous:
         previous.__del__()
     storage.cache.set(storage.cache.APP_BASE_AUTHORIZATION, authorization)
@@ -168,9 +166,9 @@ def set_authorization(authorization: Authorization) -> None:
 async def handle_CancelAuthorization(
     ctx: wire.Context, msg: CancelAuthorization
 ) -> protobuf.MessageType:
-    authorization = storage.cache.get(
+    authorization: Authorization = storage.cache.get(
         storage.cache.APP_BASE_AUTHORIZATION
-    )  # type: Authorization
+    )
     if not authorization:
         raise wire.ProcessError("No preauthorized operation")
 

core/src/apps/bitcoin/common.py

@@ -35,12 +35,14 @@ MULTISIG_OUTPUT_SCRIPT_TYPES = (
     OutputScriptType.PAYTOWITNESS,
 )
 
-CHANGE_OUTPUT_TO_INPUT_SCRIPT_TYPES = {
+CHANGE_OUTPUT_TO_INPUT_SCRIPT_TYPES: Dict[
+    EnumTypeOutputScriptType, EnumTypeInputScriptType
+] = {
     OutputScriptType.PAYTOADDRESS: InputScriptType.SPENDADDRESS,
     OutputScriptType.PAYTOMULTISIG: InputScriptType.SPENDMULTISIG,
     OutputScriptType.PAYTOP2SHWITNESS: InputScriptType.SPENDP2SHWITNESS,
     OutputScriptType.PAYTOWITNESS: InputScriptType.SPENDWITNESS,
-}  # type: Dict[EnumTypeOutputScriptType, EnumTypeInputScriptType]
+}
 INTERNAL_INPUT_SCRIPT_TYPES = tuple(CHANGE_OUTPUT_TO_INPUT_SCRIPT_TYPES.values())
 CHANGE_OUTPUT_SCRIPT_TYPES = tuple(CHANGE_OUTPUT_TO_INPUT_SCRIPT_TYPES.keys())
 

core/src/apps/bitcoin/keychain.py

@@ -19,7 +19,7 @@ if False:
     from .authorization import CoinJoinAuthorization
 
     class MsgWithCoinName(Protocol):
-        coin_name = ...  # type: str
+        coin_name: str
 
     class MsgWithAddressScriptType(Protocol):
         # XXX should be Bip32Path but that fails

core/src/apps/bitcoin/sign_tx/__init__.py

@@ -46,9 +46,9 @@ async def sign_tx(
     authorization: Optional[CoinJoinAuthorization] = None,
 ) -> TxRequest:
     if authorization:
-        approver = approvers.CoinJoinApprover(
+        approver: approvers.Approver = approvers.CoinJoinApprover(
             msg, coin, authorization
-        )  # type: approvers.Approver
+        )
     else:
         approver = approvers.BasicApprover(msg, coin)
 
@@ -64,8 +64,8 @@ async def sign_tx(
 
     signer = signer_class(msg, keychain, coin, approver).signer()
 
-    res = None  # type: Union[TxAckType, bool, None]
-    field_cache = {}  # type: FieldCache
+    res: Union[TxAckType, bool, None] = None
+    field_cache: FieldCache = {}
     while True:
         req = signer.send(res)
         if isinstance(req, tuple):

core/src/apps/bitcoin/sign_tx/approvers.py

@@ -293,7 +293,7 @@ class CoinJoinApprover(Approver):
         # Add the coordinator fee for the last group of outputs.
         self._new_group(0)
 
-        decimal_divisor = pow(10, FEE_PER_ANONYMITY_DECIMALS + 2)  # type: float
+        decimal_divisor: float = pow(10, FEE_PER_ANONYMITY_DECIMALS + 2)
         return (
             self.coordinator_fee_base
             * self.authorization.fee_per_anonymity

core/src/apps/bitcoin/sign_tx/bitcoin.py

@@ -81,10 +81,10 @@ class Bitcoin:
         self.approver = approver
 
         # set of indices of inputs which are segwit
-        self.segwit = set()  # type: Set[int]
+        self.segwit: Set[int] = set()
 
         # set of indices of inputs which are external
-        self.external = set()  # type: Set[int]
+        self.external: Set[int] = set()
 
         # transaction and signature serialization
         self.serialized_tx = writers.empty_bytearray(_MAX_SERIALIZED_CHUNK_SIZE)
@@ -102,7 +102,7 @@ class Bitcoin:
         # h_inputs is a digest of the inputs streamed for approval in Step 1, which
         # is used to ensure that the inputs streamed for verification in Step 3 are
         # the same as those in Step 1.
-        self.h_inputs = None  # type: Optional[bytes]
+        self.h_inputs: Optional[bytes] = None
 
         progress.init(tx.inputs_count, tx.outputs_count)
 

core/src/apps/bitcoin/sign_tx/matchcheck.py

@@ -43,7 +43,7 @@ class MatchChecker(Generic[T]):
     UNDEFINED = object()
 
     def __init__(self) -> None:
-        self.attribute = self.UNDEFINED  # type: Union[object, T]
+        self.attribute: Union[object, T] = self.UNDEFINED
         self.read_only = False  # Failsafe to ensure that add_input() is not accidentally called after output_matches().
 
     def attribute_from_tx(self, txio: Union[TxInput, TxOutput]) -> T:

core/src/apps/bitcoin/verification.py

@@ -31,8 +31,8 @@ class SignatureVerifier:
         coin: CoinInfo,
     ):
         self.threshold = 1
-        self.public_keys = []  # type: List[bytes]
-        self.signatures = []  # type: List[Tuple[bytes, int]]
+        self.public_keys: List[bytes] = []
+        self.signatures: List[Tuple[bytes, int]] = []
 
         if not script_sig:
             if not witness:

core/src/apps/bitcoin/verify_message.py

@@ -31,7 +31,7 @@ async def verify_message(ctx: wire.Context, msg: VerifyMessage) -> Success:
     recid = signature[0]
     if recid >= 27 and recid <= 34:
         # p2pkh
-        script_type = SPENDADDRESS  # type: EnumTypeInputScriptType
+        script_type: EnumTypeInputScriptType = SPENDADDRESS
     elif recid >= 35 and recid <= 38:
         # segwit-in-p2sh
         script_type = SPENDP2SHWITNESS

core/src/apps/common/cbor.py

@@ -149,7 +149,7 @@ def _cbor_decode(cbor: bytes) -> Tuple[Value, bytes]:
         return (data[0:ln].decode(), data[ln:])
     elif fb_type == _CBOR_ARRAY:
         if fb_aux == _CBOR_VAR_FOLLOWS:
-            res = []  # type: Value
+            res: Value = []
             data = cbor[1:]
             while True:
                 item, data = _cbor_decode(data)

core/src/apps/common/confirm.py

@@ -41,7 +41,7 @@ async def confirm(
             cancel_style,
             major_confirm,
         )
-        dialog = content  # type: ui.Layout
+        dialog: ui.Layout = content
     else:
         dialog = Confirm(
             content, confirm, confirm_style, cancel, cancel_style, major_confirm
@@ -97,7 +97,7 @@ async def hold_to_confirm(
         content.pages[-1] = HoldToConfirm(
             content.pages[-1], confirm, confirm_style, loader_style, cancel
         )
-        dialog = content  # type: ui.Layout
+        dialog: ui.Layout = content
     else:
         dialog = HoldToConfirm(content, confirm, confirm_style, loader_style, cancel)
 

core/src/apps/common/keychain.py

@@ -54,8 +54,8 @@ FORBIDDEN_KEY_PATH = wire.DataError("Forbidden key path")
 class LRUCache:
     def __init__(self, size: int) -> None:
         self.size = size
-        self.cache_keys = []  # type: List[Any]
-        self.cache = {}  # type: Dict[Any, Deletable]
+        self.cache_keys: List[Any] = []
+        self.cache: Dict[Any, Deletable] = {}
 
     def insert(self, key: Any, value: Deletable) -> None:
         if key in self.cache_keys:
@@ -126,7 +126,7 @@ class Keychain:
         new_root: Callable[[], NodeType],
     ) -> NodeType:
         cached_prefix = tuple(path[:prefix_len])
-        cached_root = self._cache.get(cached_prefix)  # type: Optional[NodeType]
+        cached_root: Optional[NodeType] = self._cache.get(cached_prefix)
         if cached_root is None:
             cached_root = new_root()
             cached_root.derive_path(cached_prefix)

core/src/apps/common/layout.py

@@ -70,7 +70,7 @@ async def show_pubkey(ctx: wire.Context, pubkey: bytes) -> None:
 
 
 async def show_xpub(ctx: wire.Context, xpub: str, desc: str, cancel: str) -> bool:
-    pages = []  # type: List[ui.Component]
+    pages: List[ui.Component] = []
     for lines in chunks(list(chunks(xpub, 16)), 5):
         text = Text(desc, ui.ICON_RECEIVE, ui.GREEN)
         text.mono(*lines)

core/src/apps/common/safety_checks.py

@@ -13,9 +13,9 @@ def read_setting() -> EnumTypeSafetyCheckLevel:
     """
     Returns the effective safety check level.
     """
-    temporary_safety_check_level = storage.cache.get(
-        APP_COMMON_SAFETY_CHECKS_TEMPORARY
-    )  # type: Optional[EnumTypeSafetyCheckLevel]
+    temporary_safety_check_level: Optional[
+        EnumTypeSafetyCheckLevel
+    ] = storage.cache.get(APP_COMMON_SAFETY_CHECKS_TEMPORARY)
     if temporary_safety_check_level is not None:
         return temporary_safety_check_level
     else:

core/src/apps/common/sdcard.py

@@ -19,7 +19,7 @@ async def _wrong_card_dialog(ctx: wire.GenericContext) -> bool:
     text.br_half()
     if SD_CARD_HOT_SWAPPABLE:
         text.normal("Please insert the", "correct SD card for", "this device.")
-        btn_confirm = "Retry"  # type: Optional[str]
+        btn_confirm: Optional[str] = "Retry"
         btn_cancel = "Abort"
     else:
         text.normal("Please unplug the", "device and insert the", "correct SD card.")
@@ -35,7 +35,7 @@ async def insert_card_dialog(ctx: wire.GenericContext) -> bool:
     text.br_half()
     if SD_CARD_HOT_SWAPPABLE:
         text.normal("Please insert your", "SD card.")
-        btn_confirm = "Retry"  # type: Optional[str]
+        btn_confirm: Optional[str] = "Retry"
         btn_cancel = "Abort"
     else:
         text.normal("Please unplug the", "device and insert your", "SD card.")

core/src/apps/debug/__init__.py

@@ -23,7 +23,7 @@ if __debug__:
     save_screen = False
     save_screen_directory = "."
 
-    reset_internal_entropy = None  # type: Optional[bytes]
+    reset_internal_entropy: Optional[bytes] = None
     reset_current_words = loop.chan()
     reset_word_index = loop.chan()
 
@@ -37,7 +37,7 @@ if __debug__:
     debuglink_decision_chan = loop.chan()
 
     layout_change_chan = loop.chan()
-    current_content = []  # type: List[str]
+    current_content: List[str] = []
     watch_layout_changes = False
 
     def screenshot() -> bool:

core/src/apps/ethereum/keychain.py

@@ -16,7 +16,7 @@ if False:
     from apps.common.keychain import MsgOut, Handler, HandlerWithKeychain
 
     class MsgWithAddressN(MessageType, Protocol):
-        address_n = ...  # type: paths.Bip32Path
+        address_n: paths.Bip32Path
 
 
 # We believe Ethereum should use 44'/60'/a' for everything, because it is

core/src/apps/management/recovery_device/homescreen.py

@@ -166,7 +166,7 @@ async def _process_words(
 
     share = None
     if not is_slip39:  # BIP-39
-        secret = recover.process_bip39(words)  # type: Optional[bytes]
+        secret: Optional[bytes] = recover.process_bip39(words)
     else:
         secret, share = recover.process_slip39(words)
 

core/src/apps/management/recovery_device/keyboard_bip39.py

@@ -115,7 +115,7 @@ class Bip39Keyboard(ui.Layout):
                 ("abc", "def", "ghi", "jkl", "mno", "pqr", "stu", "vwx", "yz")
             )
         ]
-        self.pending_button = None  # type: Optional[Button]
+        self.pending_button: Optional[Button] = None
         self.pending_index = 0
 
     def dispatch(self, event: int, x: int, y: int) -> None:

core/src/apps/management/recovery_device/keyboard_slip39.py

@@ -28,8 +28,8 @@ class InputButton(Button):
     def __init__(self, area: ui.Area, keyboard: "Slip39Keyboard") -> None:
         super().__init__(area, "")
         self.word = ""
-        self.pending_button = None  # type: Optional[Button]
-        self.pending_index = None  # type: Optional[int]
+        self.pending_button: Optional[Button] = None
+        self.pending_index: Optional[int] = None
         self.keyboard = keyboard
         self.disable()
 
@@ -118,7 +118,7 @@ class Slip39Keyboard(ui.Layout):
                 ("ab", "cd", "ef", "ghij", "klm", "nopq", "rs", "tuv", "wxyz")
             )
         ]
-        self.pending_button = None  # type: Optional[Button]
+        self.pending_button: Optional[Button] = None
         self.pending_index = 0
         self.button_sequence = ""
         self.mask = slip39.KEYBOARD_FULL_MASK

core/src/apps/management/recovery_device/layout.py

@@ -53,12 +53,12 @@ async def request_mnemonic(
 ) -> Optional[str]:
     await button_request(ctx, code=ButtonRequestType.MnemonicInput)
 
-    words = []  # type: List[str]
+    words: List[str] = []
     for i in range(word_count):
         if backup_types.is_slip39_word_count(word_count):
-            keyboard = Slip39Keyboard(
+            keyboard: Union[Slip39Keyboard, Bip39Keyboard] = Slip39Keyboard(
                 "Type word %s of %s:" % (i + 1, word_count)
-            )  # type: Union[Slip39Keyboard, Bip39Keyboard]
+            )
         else:
             keyboard = Bip39Keyboard("Type word %s of %s:" % (i + 1, word_count))
 
@@ -86,7 +86,7 @@ async def show_remaining_shares(
     shares_remaining: List[int],
     group_threshold: int,
 ) -> None:
-    pages = []  # type: List[ui.Component]
+    pages: List[ui.Component] = []
     for remaining, group in groups:
         if 0 < remaining < MAX_SHARE_COUNT:
             text = Text("Remaining Shares")

core/src/apps/monero/signing/state.py

@@ -37,11 +37,11 @@ class State:
         - spend private/public key
         - and its corresponding address
         """
-        self.creds = None  # type: Optional[AccountCreds]
+        self.creds: Optional[AccountCreds] = None
 
         # HMAC/encryption keys used to protect offloaded data
-        self.key_hmac = None  # type: Optional[bytes]
-        self.key_enc = None  # type: Optional[bytes]
+        self.key_hmac: Optional[bytes] = None
+        self.key_enc: Optional[bytes] = None
 
         """
         Transaction keys
@@ -51,8 +51,8 @@ class State:
         - for subaddresses the `r` is commonly denoted as `s`, however it is still just a random number
         - the keys are used to derive the one time address and its keys (P = H(A*r)*G + B)
         """
-        self.tx_priv = None  # type: Sc25519
-        self.tx_pub = None  # type: Ge25519
+        self.tx_priv: Sc25519 = None
+        self.tx_pub: Ge25519 = None
 
         """
         In some cases when subaddresses are used we need more tx_keys
@@ -77,8 +77,8 @@ class State:
         self.account_idx = 0
 
         # contains additional tx keys if need_additional_tx_keys is True
-        self.additional_tx_private_keys = []  # type: List[Sc25519]
-        self.additional_tx_public_keys = []  # type: List[bytes]
+        self.additional_tx_private_keys: List[Sc25519] = []
+        self.additional_tx_public_keys: List[bytes] = []
 
         # currently processed input/output index
         self.current_input_index = -1
@@ -92,36 +92,36 @@ class State:
         self.summary_outs_money = 0
 
         # output commitments
-        self.output_pk_commitments = []  # type: List[bytes]
+        self.output_pk_commitments: List[bytes] = []
 
-        self.output_amounts = []  # type: List[int]
+        self.output_amounts: List[int] = []
         # output *range proof* masks. HP10+ makes them deterministic.
-        self.output_masks = []  # type: List[Sc25519]
+        self.output_masks: List[Sc25519] = []
 
         # the range proofs are calculated in batches, this denotes the grouping
-        self.rsig_grouping = []  # type: List[int]
+        self.rsig_grouping: List[int] = []
         # is range proof computing offloaded or not
         self.rsig_offload = False
 
         # sum of all inputs' pseudo out masks
-        self.sumpouts_alphas = crypto.sc_0()  # type: Sc25519
+        self.sumpouts_alphas: Sc25519 = crypto.sc_0()
         # sum of all output' pseudo out masks
-        self.sumout = crypto.sc_0()  # type: Sc25519
+        self.sumout: Sc25519 = crypto.sc_0()
 
-        self.subaddresses = {}  # type: Subaddresses
+        self.subaddresses: Subaddresses = {}
 
         # TX_EXTRA_NONCE extra field for tx.extra, due to sort_tx_extra()
         self.extra_nonce = None
 
         # contains an array where each item denotes the input's position
         # (inputs are sorted by key images)
-        self.source_permutation = []  # type: List[int]
+        self.source_permutation: List[int] = []
 
         # Last key image seen. Used for input permutation correctness check
-        self.last_ki = None  # type: Optional[bytes]
+        self.last_ki: Optional[bytes] = None
 
         # Encryption key to release to host after protocol ends without error
-        self.opening_key = None  # type: Optional[bytes]
+        self.opening_key: Optional[bytes] = None
 
         # Step transition automaton
         self.last_step = self.STEP_INIT
@@ -132,7 +132,7 @@ class State:
         See Monero-Trezor documentation section 3.3 for more details.
         """
         self.tx_prefix_hasher = KeccakXmrArchive()
-        self.tx_prefix_hash = None  # type: Optional[bytes]
+        self.tx_prefix_hash: Optional[bytes] = None
 
         """
         Full message hasher/hash that is to be signed using MLSAG.
@@ -140,7 +140,7 @@ class State:
         See Monero-Trezor documentation section 3.3 for more details.
         """
         self.full_message_hasher = PreMlsagHasher()
-        self.full_message = None  # type: Optional[bytes]
+        self.full_message: Optional[bytes] = None
 
     def mem_trace(self, x=None, collect=False):
         if __debug__:

core/src/apps/webauthn/confirm.py

@@ -10,7 +10,7 @@ DEFAULT_ICON = "apps/webauthn/res/icon_webauthn.toif"
 
 class ConfirmInfo:
     def __init__(self) -> None:
-        self.app_icon = None  # type: Optional[bytes]
+        self.app_icon: Optional[bytes] = None
 
     def get_header(self) -> str:
         raise NotImplementedError

core/src/apps/webauthn/credential.py

@@ -55,11 +55,11 @@ _U2F_KEY_PATH = const(0x8055_3246)
 
 class Credential:
     def __init__(self) -> None:
-        self.index = None  # type: Optional[int]
-        self.id = b""  # type: bytes
-        self.rp_id = ""  # type: str
-        self.rp_id_hash = b""  # type: bytes
-        self.user_id = None  # type: Optional[bytes]
+        self.index: Optional[int] = None
+        self.id: bytes = b""
+        self.rp_id: str = ""
+        self.rp_id_hash: bytes = b""
+        self.user_id: Optional[bytes] = None
 
     def __lt__(self, other: "Credential") -> bool:
         raise NotImplementedError
@@ -107,14 +107,14 @@ class Credential:
 class Fido2Credential(Credential):
     def __init__(self) -> None:
         super().__init__()
-        self.rp_name = None  # type: Optional[str]
-        self.user_name = None  # type: Optional[str]
-        self.user_display_name = None  # type: Optional[str]
-        self.creation_time = 0  # type: int
-        self.hmac_secret = False  # type: bool
-        self.use_sign_count = False  # type: bool
-        self.algorithm = _DEFAULT_ALGORITHM  # type: int
-        self.curve = _DEFAULT_CURVE  # type: int
+        self.rp_name: Optional[str] = None
+        self.user_name: Optional[str] = None
+        self.user_display_name: Optional[str] = None
+        self.creation_time: int = 0
+        self.hmac_secret: bool = False
+        self.use_sign_count: bool = False
+        self.algorithm: int = _DEFAULT_ALGORITHM
+        self.curve: int = _DEFAULT_CURVE
 
     def __lt__(self, other: Credential) -> bool:
         # Sort FIDO2 credentials newest first amongst each other.
@@ -359,7 +359,7 @@ class Fido2Credential(Credential):
 class U2fCredential(Credential):
     def __init__(self) -> None:
         super().__init__()
-        self.node = None  # type: Optional[bip32.HDNode]
+        self.node: Optional[bip32.HDNode] = None
 
     def __lt__(self, other: "Credential") -> bool:
         # Sort U2F credentials after FIDO2 credentials.

core/src/apps/webauthn/fido2.py

@@ -563,7 +563,7 @@ async def handle_reports(iface: io.HID) -> None:
                 dialog_mgr.get_cid(),
                 _CID_BROADCAST,
             ):
-                resp = cmd_error(req.cid, _ERR_CHANNEL_BUSY)  # type: Optional[Cmd]
+                resp: Optional[Cmd] = cmd_error(req.cid, _ERR_CHANNEL_BUSY)
             else:
                 resp = dispatch_cmd(req, dialog_mgr)
             if resp is not None:
@@ -771,7 +771,7 @@ class Fido2Unlock(Fido2State):
         super().__init__(req.cid, dialog_mgr.iface)
         self.process_func = process_func
         self.req = req
-        self.resp = None  # type: Optional[Cmd]
+        self.resp: Optional[Cmd] = None
         self.dialog_mgr = dialog_mgr
 
     async def confirm_dialog(self) -> Union[bool, "State"]:
@@ -992,11 +992,11 @@ class DialogManager:
         self._clear()
 
     def _clear(self) -> None:
-        self.state = None  # type: Optional[State]
+        self.state: Optional[State] = None
         self.deadline = 0
         self.result = _RESULT_NONE
-        self.workflow = None  # type: Optional[loop.spawn]
-        self.keepalive = None  # type: Optional[Coroutine]
+        self.workflow: Optional[loop.spawn] = None
+        self.keepalive: Optional[Coroutine] = None
 
     def _workflow_is_running(self) -> bool:
         return self.workflow is not None and not self.workflow.finished
@@ -1211,7 +1211,7 @@ def cmd_wink(req: Cmd) -> Cmd:
 
 def msg_register(req: Msg, dialog_mgr: DialogManager) -> Cmd:
     if not config.is_unlocked():
-        new_state = U2fUnlock(req.cid, dialog_mgr.iface)  # type: State
+        new_state: State = U2fUnlock(req.cid, dialog_mgr.iface)
         dialog_mgr.set_state(new_state)
         return msg_error(req.cid, _SW_CONDITIONS_NOT_SATISFIED)
 
@@ -1292,7 +1292,7 @@ def msg_register_sign(challenge: bytes, cred: U2fCredential) -> bytes:
 
 def msg_authenticate(req: Msg, dialog_mgr: DialogManager) -> Cmd:
     if not config.is_unlocked():
-        new_state = U2fUnlock(req.cid, dialog_mgr.iface)  # type: State
+        new_state: State = U2fUnlock(req.cid, dialog_mgr.iface)
         dialog_mgr.set_state(new_state)
         return msg_error(req.cid, _SW_CONDITIONS_NOT_SATISFIED)
 
@@ -1427,7 +1427,7 @@ def credentials_from_descriptor_list(
 def distinguishable_cred_list(credentials: Iterable[Credential]) -> List[Credential]:
     """Reduces the input to a list of credentials which can be distinguished by
     the user. It is assumed that all input credentials share the same RP ID."""
-    cred_list = []  # type: List[Credential]
+    cred_list: List[Credential] = []
     for cred in credentials:
         for i, prev_cred in enumerate(cred_list):
             if prev_cred.account_name() == cred.account_name():