code: func GetInt64Ptr(d *schema.ResourceData, key string) *int64 {
  	v, e := d.GetOkExists(key)
  	if e {
  		return Int64Ptr(int64(v.(int)))
  	}
  	return nil
  }
docs: // GetInt64Ptr reads a ResourceData and returns an appropriate *int64 for the
  // state of the definition. nil is returned if it does not exist.