[Typing][C-17] Add type annotations for python/paddle/distributed/communication/gather.py (#66276)

Author: BHmingyang

python/paddle/distributed/communication/gather.py

@@ -13,11 +13,26 @@
 # limitations under the License.
 
 
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
 from paddle import framework
 from paddle.distributed.communication import stream
 
+if TYPE_CHECKING:
+    from paddle import Tensor
+    from paddle.base.core import task
+    from paddle.distributed.communication.group import Group
+
 
-def gather(tensor, gather_list=None, dst=0, group=None, sync_op=True):
+def gather(
+    tensor: Tensor,
+    gather_list: list[Tensor] = None,
+    dst: int = 0,
+    group: Group | None = None,
+    sync_op: bool = True,
+) -> task | None:
     """
 
     Gather tensors from all participators.