client = Client() # will make unauthenticated requests
auth_client = AuthenticatedClient(token='my-token') # will make authenticated requests

auth_client1 = AuthenticatedClient(token='user1-token') # will make authenticated requests for user1
auth_client2 = AuthenticatedClient(token='user2-token') # will make authenticated requests for user2

client = Client()
client.with_authorization_token(token='user1-token')
client.request() # will make auth requests for user1
client.with_authorization_token(token='user2-token')

from base64 import b64encode
from typing import Dict, Generic, TypeVar, cast
from attrs import define, evolve, field
class Unauthenticated: ...
class Authenticated: ...
_State = TypeVar("_State")
@define
class _Client(Generic[_State]):
 _headers: Dict[str, str] = field(factory=dict, kw_only=True)
 def with_headers(self, headers: Dict[str, str]) -> "Client":
 return evolve(self, _headers={**self._headers, **headers})
 def with_authorization_token(
 self: "Client",
 token: str,
 prefix: str = "Bearer",
 ) -> "AuthClient":
 return cast("AuthClient", self.with_headers({"Authorization": f"{prefix} {token}"}))
 def with_authorization_basic(
 self: "Client",
 username: str,
 password: str,
 prefix: str = "Basic",
 ) -> "AuthClient":
 encoded_credentials = b64encode(f"{username}:{password}".encode()).decode()
 return cast("AuthClient", self.with_headers({"Authorization": f"{prefix} {encoded_credentials}"}))
 def remove_headers(self: "AuthClient") -> "Client":
 return evolve(self, _headers={})
Client = _Client[Unauthenticated]
AuthClient = _Client[Authenticated]
def my_func(client: AuthClient) -> None:
 # only accepts authenticated clients
 print("got headers:", client._headers)
# --- usage demos ---
c0 = Client() # Unauthenticated
my_func(c0) # static type error
c1 = c0.with_authorization_token("my-token") # Authenticated
my_func(c1) # ok
c2 = c1.remove_headers() # back to Unauthenticated
my_func(c2) # static type error
c1 = c0.with_authorization_basic("my-username", "my-password") # Authenticated
my_func(c1) # ok