The response for an HTTP request. Returned from the Http service.

class HttpResponse {
 /**
  * The HTTP status code.
  */
 int status;

 /**
  * DEPRECATED
  */
 var responseText;
 Map _headers;

 /**
  * The [HttpResponseConfig] object which contains the requested URL
  */
 HttpResponseConfig config;

 /**
  * Constructor
  */
 HttpResponse([this.status, this.responseText, this._headers, this.config]);

 /**
  * Copy constructor.  Creates a clone of the response, optionally with new
  * data.
  */
 HttpResponse.copy(HttpResponse r, {data}) {
   status = r.status;
   responseText = data == null ? r.responseText : data;
   _headers = r._headers == null ? null : new Map.from(r._headers);
   config = r.config;
 }

 /**
  * The response's data.  Either a string or a transformed object.
  */
 get data => responseText;

 /**
  * The response's headers.  Without parameters, this method will return the
  * [Map] of headers.  With [key] parameter, this method will return the specific
  * header.
  */
 headers([String key]) {
   if (key == null) {
     return _headers;
   }
   if (_headers.containsKey(key)) {
     return _headers[key];
   }
   return null;
 }

 /**
  * Useful for debugging.
  */
 toString() => 'HTTP $status: $data';
}