chore(client): improve copy method (#246)

src/anthropic/_client.py

@@ -4,8 +4,8 @@
 
 import os
 import asyncio
-from typing import Union, Mapping
-from typing_extensions import override
+from typing import Any, Union, Mapping
+from typing_extensions import Self, override
 
 import httpx
 from tokenizers import Tokenizer  # type: ignore[import]
@@ -194,12 +194,10 @@ def copy(
         set_default_headers: Mapping[str, str] | None = None,
         default_query: Mapping[str, object] | None = None,
         set_default_query: Mapping[str, object] | None = None,
-    ) -> Anthropic:
+        _extra_kwargs: Mapping[str, Any] = {},
+    ) -> Self:
         """
         Create a new client instance re-using the same options given to the current client with optional overriding.
-
-        It should be noted that this does not share the underlying httpx client class which may lead
-        to performance issues.
         """
         if default_headers is not None and set_default_headers is not None:
             raise ValueError("The `default_headers` and `set_default_headers` arguments are mutually exclusive")
@@ -247,6 +245,7 @@ def copy(
             max_retries=max_retries if is_given(max_retries) else self.max_retries,
             default_headers=headers,
             default_query=params,
+            **_extra_kwargs,
         )
 
     # Alias for `copy` for nicer inline usage, e.g.
@@ -455,12 +454,10 @@ def copy(
         set_default_headers: Mapping[str, str] | None = None,
         default_query: Mapping[str, object] | None = None,
         set_default_query: Mapping[str, object] | None = None,
-    ) -> AsyncAnthropic:
+        _extra_kwargs: Mapping[str, Any] = {},
+    ) -> Self:
         """
         Create a new client instance re-using the same options given to the current client with optional overriding.
-
-        It should be noted that this does not share the underlying httpx client class which may lead
-        to performance issues.
         """
         if default_headers is not None and set_default_headers is not None:
             raise ValueError("The `default_headers` and `set_default_headers` arguments are mutually exclusive")
@@ -508,6 +505,7 @@ def copy(
             max_retries=max_retries if is_given(max_retries) else self.max_retries,
             default_headers=headers,
             default_query=params,
+            **_extra_kwargs,
         )
 
     # Alias for `copy` for nicer inline usage, e.g.