code: function(resolveReference) {
      const result = this.node();
      let relative = false;
      if (this.token === this.tok.T_NAMESPACE) {
        this.next().expect(this.tok.T_NS_SEPARATOR) && this.next();
        relative = true;
      }
      const names = this.read_list(
        this.tok.T_STRING,
        this.tok.T_NS_SEPARATOR,
        true
      );
      if (
        !relative &&
        names.length === 1 &&
        (resolveReference || this.token !== "(")
      ) {
        if (names[0].toLowerCase() === "parent") {
          return result("parentreference", names[0]);
        } else if (names[0].toLowerCase() === "self") {
          return result("selfreference", names[0]);
        }
      }
      return result("classreference", names, relative);
    }
docs: Reads a namespace name
  ```ebnf
  namespace_name ::= T_NS_SEPARATOR? (T_STRING T_NS_SEPARATOR)* T_STRING
  ```
  @see http://php.net/manual/en/language.namespaces.rules.php
  @return {Reference}