SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Function map (alias m) (children 1)
     ExpressionList (children 2)
      Literal \'a\'
      Literal Tuple_(UInt64_1, \'foo\')
   ExpressionList (children 2)
    Function arrayElementOrNull (children 1)
     ExpressionList (children 2)
      Identifier m
      Literal \'a\'
    Function arrayElementOrNull (children 1)
     ExpressionList (children 2)
      Identifier m
      Literal \'c\'
