As looks up errors whose label is the same as the specific label and return a wrapped error.

From creates an Error with string label.

From creates an Error with string label, but separated from wrapped error message when the error is printed.

Get gets Error struct from an error.

Is looks up errors whose label is the same as the specific label and return true if it was found.

With returns a new constructor to generate an Error with specific label.

ErrInvalidParams represents the params are invalid, such as empty string.

ErrNotFound indicates something was not found.

ErrNotImplemented indicates unimplemented.

Error can hold an error together with label.