SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function mapFromArrays (children 1)
     ExpressionList (children 2)
      Literal Array_[\'a\', UInt64_2]
      Literal Array_[UInt64_4, UInt64_5]