code: function(method){
              method = this.string(method);
              if(methods.indexOf(method.toLowerCase()) < 0){
                  throw new TypeError('a method in [' + methods.join(', ') + '] is expected, but ' + method + ' given');
              }
              return method.toLowerCase();
          }
docs: Check whether the given HTTP method is supported.
  The list of supported methods is set above, in the {@link methods} variable.
  @param {String} method
  @returns {String} method (but to lower case)
  @throws {TypeError} if the method isn't supported