expression : INTEGER OP expression
             { return &::expression(@item) }
             | VARIABLE OP expression
             { return &::expression(@item) }
             | INTEGER
             | VARIABLE
             { return $::VARIABLE{$item{VARIABLE}} }

##</code><code>##

  expression : INTEGER OP expression
             { $return = &::expression(@item) }
             | VARIABLE OP expression
             { $return = &::expression(@item) }
             | INTEGER
             | VARIABLE
             { $return = $::VARIABLE{$item{VARIABLE}} }