code: func GetBoolPtr(d *schema.ResourceData, key string) *bool {
  	v, e := d.GetOkExists(key)
  	if e {
  		return BoolPtr(v.(bool))
  	}
  	return nil
  }
docs: // GetBoolPtr reads a ResourceData and returns an appropriate *bool for the
  // state of the definition. nil is returned if it does not exist.