writeHeaders(headers) {
	    this.headers = headers;
	    this._parseContentLength();
	    this._parseContentType();

	    if (!this._parser) {
	      this._error(
	        new FormidableError(
	          'no parser found',
	          errors.noParser,
	          415, // Unsupported Media Type
	        ),
	      );
	      return;
	    }

	    this._parser.once('error', (error) => {
	      this._error(error);
	    });
	  }
Enable transmission of cookies with x-domain requests.

Note that for this to work the origin must not be
using "Access-Control-Allow-Origin" with a wildcard,
and also must set "Access-Control-Allow-Credentials"
to "true".

@api public