code: function(name, value){
                  data.headers = data.headers || {};
  
                  validators.string(name);
                  if(typeof value !== 'undefined'){
                      validators.string(value);
  
                      data.headers[name] = value;
  
                      return this;
                  }
  
                  return data.headers[name];
              }
docs: HTTP Request Header getter/setter.
  
  @example aja().header('Content-Type', 'application/json');
  
  @throws TypeError
  @param {String} name - the name of the header to get/set
  @param {String} [value] - the value of the header to set
  @returns {Aja|String} chains or get the header from the given name