'Return an iterable corresponding to the
input row specifier.
Parameters
row_specifier : int, list, ndarray, or slice'

def get_row_specifier(self, row_specifier):

    if isinstance(row_specifier, (int, np.integer)):
        return (row_specifier,)
    elif isinstance(row_specifier, (list, np.ndarray)):
        return row_specifier
    elif isinstance(row_specifier, slice):
        col_len = len(self.columns[0])
        return range(*row_specifier.indices(col_len))
    raise ValueError(u'Expected    int,    array    of    ints,    or    slice    but    got    {0}    in    remove_rows'.format(row_specifier))
