  parseResponseHeaderString: function (string) {
    if (!string || string === '' || string.indexOf('\r\n') === -1) {
      return {
        version: 'HTTP/1.1',
        statusText: ''
      }
    }

    var lines = string.split('\r\n')
    var status = lines.shift()

    // Remove empty strings
    lines = lines.filter(Boolean)

    // Parse status line
    var output = this.parseStartLine(status)

    // init headers object & array
    output.headersObj = {}
    output.headersArr = []

    // Parse headers
    var header
    for (var i = lines.length; i--;) {
      header = this.parseHeaderLine(lines[i])

      output.headersArr.push(header)
      output.headersObj[header.name] = header.value
    }

    return output
  },