SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Literal \'number: 2\' (alias mm)
   ExpressionList (children 1)
    Function extract (children 1)
     ExpressionList (children 2)
      Identifier mm
      Literal \'\\\\d+\'