errors

var As = errors.As

As finds the first error in err's chain that matches target, and if one is found, sets target to that error value and returns true. Otherwise, it returns false.

var Errorf = xerrors.Errorf

Errorf formats according to a format specifier and returns the string as a value that satisfies error.

var Is = errors.Is

Is reports whether any error in err's chain matches target.

var New = errors.New

New returns an error that formats as the given text. Each call to New returns a distinct error value even if the text is identical.