// TypeAndValue reports the type and value (for constants)
// of the corresponding expression. If the constant is used in
// an expression at run time (for instance in an assignment),
// GoValue contains the corresponding machine (materialized)
// value. The type of GoValue is the underlying type of the
// constant (a Go basic type permissible as constant type).
type TypeAndValue struct {
    mode  operandMode
    Type  Type
    Value constant.Value
    GoValue interface{}
}