def _is_enlargement(locator, global_index):
    """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 !
    """
    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
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 !