code: def _is_enlargement(locator, global_index):
      
      if (
          is_list_like(locator)
          and not is_slice(locator)
          and len(locator) > 0
          and not is_boolean_array(locator)
          and (isinstance(locator, type(global_index[0])) and locator not in global_index)
      ):
          n_diff_elems = len(pandas.Index(locator).difference(global_index))
          is_enlargement_boolean = n_diff_elems > 0
          return is_enlargement_boolean
      return False
docs: Determine if a locator will enlarge the global index.
  
      Enlargement happens when you trying to locate using labels isn't in the
      original index. In other words, enlargement == adding NaNs !