code: function(name) {
      var regexp, idx,
        length = this.extraHeaders.length,
        header = this.headers[Utils.headerize(name)];
  
      if(header) {
        if(header[0]) {
          return header[0];
        }
      } else {
        regexp = new RegExp('^\\s*'+ name +'\\s*:','i');
        for (idx=0; idx<length; idx++) {
          header = this.extraHeaders[idx];
          if (regexp.test(header)) {
            return header.substring(header.indexOf(':')+1).trim();
          }
        }
      }
  
      return;
    }
docs: Get the value of the given header name at the given position.
  -param {String} name header name
  -returns {String|undefined} Returns the specified header, null if header doesn't exist.