As is a wrapper of built-in errors.As.

Cause returns the result of repeatedly calling the Unwrap method on err, if err's type implements an Unwrap method.

Is is a wrapper of built-in errors.Is.

Newf formats according to a format specifier and returns a new error with a stacktrace with recent call frames.

Unwrap is a wrapper of built-in errors.Unwrap.

Wrapf returns a new error by formatting the error message with the supplied format specifier and wrapping another error with a stacktrace containing recent call frames.