'Utility function used currently only by _init_from_coldefs
to help convert columns from binary format to ASCII format or vice
versa if necessary (otherwise performs a straight copy).'

def _copy_column(self, column):

    if isinstance(column.format, self._col_format_cls):
        return column.copy()
    new_column = column.copy()
    new_column.format = self._col_format_cls.from_column_format(column.format)
    if (not isinstance(new_column.format, _AsciiColumnFormat)):
        new_column.start = None
        if (new_column.null is not None):
            new_column.null = None
    else:
        if (new_column.null is not None):
            new_column.null = DEFAULT_ASCII_TNULL
        if ((new_column.disp is not None) and new_column.disp.upper().startswith('L')):
            new_column.disp = None
    return new_column
