code: def _table_arg_to_table(value, default_project=None):
      
      if isinstance(value, six.string_types):
          value = TableReference.from_string(value, default_project=default_project)
      if isinstance(value, TableReference):
          value = Table(value)
      if isinstance(value, TableListItem):
          newvalue = Table(value.reference)
          newvalue._properties = value._properties
          value = newvalue
  
      return value
docs: Helper to convert a string or TableReference to a Table.
  
      This function keeps Table and other kinds of objects unchanged.