code: function() {
      let result = [];
  
      while (this.token !== this.EOF && this.token !== "}") {
        if (this.token === this.tok.T_COMMENT) {
          result.push(this.read_comment());
          continue;
        }
  
        if (this.token === this.tok.T_DOC_COMMENT) {
          result.push(this.read_doc_comment());
          continue;
        }
  
        // read member flags
        const flags = this.read_member_flags(true);
  
        // check constant
        if (this.token == this.tok.T_CONST) {
          const constants = this.read_constant_list(flags);
          if (this.expect(";")) {
            this.next();
          }
          result = result.concat(constants);
        } else if (this.token === this.tok.T_FUNCTION) {
          // reads a function
          const method = this.read_function_declaration(2, flags);
          method.parseFlags(flags);
          result.push(method);
          if (this.expect(";")) {
            this.next();
          }
        } else {
          // raise an error
          this.error([this.tok.T_CONST, this.tok.T_FUNCTION]);
          this.next();
        }
      }
      if (this.expect("}")) {
        this.next();
      }
      return result;
    }
docs: Reads an interface body
  ```ebnf
  interface_body ::= (member_flags? (T_CONST | T_FUNCTION))*
  ```