'append the given column expression to the columns clause of this
select() construct.
This is an **in-place** mutation method; the
:meth:`~.Select.column` method is preferred, as it provides standard
:term:`method chaining`.'

def append_column(self, column):

    self._reset_exported()
    column = _interpret_as_column_or_from(column)
    if isinstance(column, ScalarSelect):
        column = column.self_group(against=operators.comma_op)
    self._raw_columns = (self._raw_columns + [column])
