code: def is_valid(cls, oid):
          
          if not oid:
              return False
  
          try:
              ObjectId(oid)
              return True
          except (InvalidId, TypeError):
              return False
docs: Checks if a `oid` string is valid or not.
  
          :Parameters:
            - `oid`: the object id to validate
  
          .. versionadded:: 2.3