code: func taskFault(err error) (types.BaseMethodFault, bool) {
  	if te, ok := err.(task.Error); ok {
  		return te.Fault(), true
  	}
  	return nil, false
  }
docs: // taskFault extracts the task fault from a supplied task.Error. Check the
  // returned boolean value to see if the fault was extracted correctly, after
  // which you will need to do further checking.