code: func SegmentExternalBegin(id, parent int64, host, name string) (int64, error) {
  	cname := C.CString(name)
  	defer C.free(unsafe.Pointer(cname))
  
  	chost := C.CString(host)
  	defer C.free(unsafe.Pointer(chost))
  
  	return errNoLong(C.newrelic_segment_external_begin(C.long(id), C.long(parent), chost, cname))
  }
docs: /*
   * Identify the beginning of a segment that performs an external service.
   *
   * @param transaction_id  id of transaction
   * @param parent_segment_id  id of parent segment
   * @param host  name of the host of the external call
   * @param name  name of the external transaction
   * @return  segment id on success, else negative warning code or error code
   */