function acceptRequired(node, name) {
        this.acceptKey(node, name);

        if (!node[name]) {
          throw new _exception2['default'](node.type + ' requires ' + name);
        }
      }
// required keys are not removed.
required keys are not removed.
required keys are not removed .
function acceptRequired(node, name) {
        this.acceptKey(node, name);
        if (!node[name]) {
          throw new _exception2['default'](node.type + ' requires ' + name);
        }
      }
function acceptRequired ( node , name ) { this . acceptKey ( node , name ) ; if ( ! node [ name ] ) { throw new _exception2 [ 'default' ] ( node . type + ' requires ' + name ) ; } }
required keys are not removed.
required keys are not removed .