docs: function isInstance(node) {
    if (node.type === 'Identifier') {
      if (currentOptions.angular) {
        if (instanceVarsRegExp.angular.test(node.name)) {
          return true;
        }
      } else {
        if (instanceVarsRegExp.noangular.test(node.name)) {
          return true;
        }
      }
    }
    if (node.type === 'CallExpression') {
      if (isConstructor(node.callee)) {
        return true;
      }
      if (node.callee.type === 'MemberExpression') {
        if (isInstance(node.callee.object)) {
          if (node.callee.property.type === 'Identifier' &&
              constants.METHODS.CHAIN.indexOf(node.callee.property.name) !== -1) {
            return true;
          }
        }
      }
    }
    return false;
  }