Accept partial file names (google-gemini#386)

Adds prefix files/ if not present

Change-Id: Iac5c4d0934620f2462cf15ae519474b0ce7908da

google/generativeai/files.py

@@ -81,16 +81,20 @@ def list_files(page_size=100) -> Iterable[file_types.File]:
         yield file_types.File(proto)
 
 
-def get_file(name) -> file_types.File:
+def get_file(name: str) -> file_types.File:
     """Calls the API to retrieve a specified file using a supported file service."""
+    if "/" not in name:
+        name = f"files/{name}"
     client = get_default_file_client()
     return file_types.File(client.get_file(name=name))
 
 
-def delete_file(name):
+def delete_file(name: str | file_types.File | protos.File):
     """Calls the API to permanently delete a specified file using a supported file service."""
     if isinstance(name, (file_types.File, protos.File)):
         name = name.name
+    elif "/" not in name:
+        name = f"files/{name}"
     request = protos.DeleteFileRequest(name=name)
     client = get_default_file_client()
     client.delete_file(request=request)