SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 2)
    Function greatest (children 1)
     ExpressionList (children 2)
      Literal NULL
      Literal Float64_1.1
    Function least (children 1)
     ExpressionList (children 2)
      Literal NULL
      Literal Float64_1.1
