message: reduce is_some function
diff: @@ -251,8 +251,8 @@ impl<'a> Evaluated<'a> {
  match self {
  Evaluated::ValueRef(v) => v.is_some(),
  Evaluated::Value(v) => v.is_some(),
  - Evaluated::Literal(v) => *v != AstValue::Null,
  - Evaluated::LiteralRef(v) => **v != AstValue::Null,
  + Evaluated::Literal(v) => v != &AstValue::Null,
  + Evaluated::LiteralRef(v) => v != &&AstValue::Null,
  Evaluated::StringRef(_v) => true,
  }
  }
  