@OnlyIfDescendedFrom(['alter'])
  def visit_add_column(self, tokens, table):
    """Add a column definition to a table declaration."""
    base_type = 'unknown'
    if 'type' in tokens['column_definition']:
      base_type = tokens['column_definition']['type'][0]
    if tokens['column_definition']['type'] in 'values':
      values = tokens['column_definition']['type']['values']
      base_type = '%s(%s)' % (base_type,
                              ','.join("'%s'" % x.replace("'", "''")
                                       for x in values))
    try:
      column = table.AddColumn(tokens['column_spec']['column'][0], base_type)
      self.visit(tokens, table=table, column=column)
    except schema.DuplicateNameException:
      self.AddError(tokens, 'Column already exists.')
dataset/ETHPy150Open google/mysql-tools/parser_lib/validator.py/AlterChecker.visit_add_column/swapped operands of `in`