package namecheck import "fmt" type ErrSocialNetwork interface { Error() error Unwrap() error } type ErrUnknownAvailability struct { Username string Cause error } func (e *ErrUnknownAvailability) Error() string { return fmt.Sprintf("Error during check for username '%s'\n[%s]\n", e.Username, e.Cause) } func (e *ErrUnknownAvailability) Unwrap() error { return e.Cause }