Sync eth_keys stub with actual code

stubs/eth_keys/datatypes.pyi

@@ -1,25 +1,37 @@
 import collections
-from typing import Any, Optional, Text, Tuple
+from typing import (
+    Any,
+    Optional,
+    Tuple,
+    Type,
+    Union
+)
+
+from backends.base import BaseECCBackend
+
+class LazyBackend:
+    def __init__(
+            self,
+            backend: 'Union[BaseECCBackend, Type[BaseECCBackend], str]'=None
+            ) -> None: ...
 
-class BackendProxied:
     @property
-    def backend(self): ...
+    def backend(self) -> BaseECCBackend: ...
     @classmethod
-    def get_backend(cls): ...
+    def get_backend(cls) -> BaseECCBackend: ...
 
 class BaseKey(collections.abc.ByteString, collections.Hashable):
-    def to_hex(self) -> Text: ...
+    def to_hex(self) -> str: ...
     def to_bytes(self) -> bytes: ...
-    def __hash__(self): ...
-    def __unicode__(self): ...
-    def __int__(self): ...
-    def __len__(self): ...
-    def __getitem__(self, index): ...
+    def __hash__(self) -> int: ...
+    def __int__(self) -> int: ...
+    def __len__(self) -> int: ...
+    def __getitem__(self, index: int) -> int: ...  # type: ignore
     def __eq__(self, other: Any) -> bool: ...
-    def __index__(self): ...
-    def __hex__(self) -> Text: ...
+    def __index__(self) -> int: ...
+    def __hex__(self) -> str: ...
 
-class PublicKey(BaseKey, BackendProxied):
+class PublicKey(BaseKey, LazyBackend):
     def __init__(self, public_key_bytes: bytes) -> None: ...
     @classmethod
     def from_private(cls, private_key: PrivateKey) -> PublicKey: ...
@@ -33,13 +45,13 @@ class PublicKey(BaseKey, BackendProxied):
     def to_address(self) -> bytes: ...
     def to_canonical_address(self) -> bytes: ...
 
-class PrivateKey(BaseKey, BackendProxied):
+class PrivateKey(BaseKey, LazyBackend):
     public_key: PublicKey = ...
     def __init__(self, private_key_bytes: bytes) -> None: ...
     def sign_msg(self, message: bytes) -> Signature: ...
     def sign_msg_hash(self, message_hash: bytes) -> Signature: ...
 
-class Signature(collections.abc.ByteString, BackendProxied):
+class Signature(collections.abc.ByteString, LazyBackend):
     r: int = ...
     s: int = ...
     v: int = ...
@@ -58,18 +70,17 @@ class Signature(collections.abc.ByteString, BackendProxied):
     def s(self, value: int) -> None: ...
     @property
     def vrs(self) -> Tuple[int, int, int]: ...
-    def to_hex(self) -> Text: ...
+    def to_hex(self) -> str: ...
     def to_bytes(self) -> bytes: ...
-    def __hash__(self): ...
+    def __hash__(self) -> int: ...
     def __bytes__(self) -> bytes: ...
-    def __unicode__(self): ...
-    def __len__(self): ...
-    def __eq__(self, other): ...
-    def __getitem__(self, index): ...
+    def __len__(self) -> int: ...
+    def __eq__(self, other: Any) -> bool: ...
+    def __getitem__(self, index: int) -> int: ...  # type: ignore
     def verify_msg(self, message: bytes, public_key: PublicKey) -> bool: ...
     def verify_msg_hash(self, message_hash: bytes, public_key: PublicKey) -> bool: ...
     def recover_public_key_from_msg(self, message: bytes) -> PublicKey: ...
     def recover_public_key_from_msg_hash(self, message_hash: bytes) -> PublicKey: ...
-    def __index__(self): ...
-    def __hex__(self) -> Text: ...
-    def __int__(self): ...
+    def __index__(self) -> int: ...
+    def __hex__(self) -> str: ...
+    def __int__(self) -> int: ...

stubs/eth_keys/main.pyi

@@ -1,21 +1,24 @@
-from eth_keys.datatypes import PrivateKey, PublicKey, Signature
-from typing import Any, Optional, Union
+from typing import (
+    Any,
+    Optional,
+    Type,
+    Union
+)
 
-def backend_property_proxy(name): ...
+from .datatypes import (
+    LazyBackend,
+)
 
-class KeyAPI:
-    backend: Any = ...
-    def __init__(self, backend: Optional[Any] = ...) -> None: ...
-    @property
-    def backend(self): ...
-    @backend.setter
-    def backend(self, value): ...
-    PublicKey: Any = ...
-    PrivateKey: Any = ...
-    Signature: Any = ...
-    def ecdsa_sign(self, message_hash: bytes, private_key: Union[PrivateKey, bytes]) -> Optional[Signature]: ...
-    def ecdsa_verify(self, message_hash: bytes, signature: Union[Signature, bytes], public_key: Union[PublicKey, bytes]) -> Optional[bool]: ...
-    def ecdsa_recover(self, message_hash: bytes, signature: Union[Signature, bytes]) -> Optional[PublicKey]: ...
-    def private_key_to_public_key(self, private_key): ...
+import datatypes
+
+
+class KeyAPI(LazyBackend):
+    PublicKey: Type[datatypes.PublicKey] = ...
+    PrivateKey: Type[datatypes.PrivateKey] = ...
+    Signature: Type[datatypes.Signature] = ...
+    def ecdsa_sign(self, message_hash: bytes, private_key: Union[datatypes.PrivateKey, bytes]) -> Optional[datatypes.Signature]: ...
+    def ecdsa_verify(self, message_hash: bytes, signature: Union[datatypes.Signature, bytes], public_key: Union[datatypes.PublicKey, bytes]) -> Optional[bool]: ...
+    def ecdsa_recover(self, message_hash: bytes, signature: Union[datatypes.Signature, bytes]) -> Optional[datatypes.PublicKey]: ...
+    def private_key_to_public_key(self, private_key: datatypes.PrivateKey) -> datatypes.PublicKey: ...
 
 lazy_key_api: KeyAPI