Update check_username method

pyrogram/methods/users/check_username.py

@@ -16,6 +16,8 @@
 #  You should have received a copy of the GNU Lesser General Public License
 #  along with Pyrogram.  If not, see <http://www.gnu.org/licenses/>.
 
+from typing import Union
+
 import pyrogram
 from pyrogram import raw
 
@@ -23,6 +25,7 @@ from pyrogram import raw
 class CheckUsername:
     async def check_username(
         self: "pyrogram.Client",
+        chat_id: Union[int, str],
         username: str
     ) -> bool:
         """Check if a username is available.
@@ -30,6 +33,9 @@ class CheckUsername:
         .. include:: /_includes/usable-by/users.rst
 
         Parameters:
+            chat_id (``int`` | ``str``):
+                Unique identifier (int) or username (str) of the target chat.
+
             username (``str``):
                 Username to check.
 
@@ -39,13 +45,22 @@ class CheckUsername:
         Example:
             .. code-block:: python
 
-                await app.check_username("username")
+                await app.check_username("me", "username")
         """
+        peer = await self.resolve_peer(chat_id)
 
-        return bool(
-            await self.invoke(
+        if isinstance(peer, raw.types.InputPeerChannel):
+            r = await self.invoke(
+                raw.functions.channels.CheckUsername(
+                    channel=peer,
+                    username=username
+                )
+            )
+        else:
+            r = await self.invoke(
                 raw.functions.account.CheckUsername(
                     username=username
                 )
             )
-        )
+
+        return bool(r)