type BaseError string

type Error interface {
	// Error returns the error string
	Error() string

	// Is returns whether an error is of type [supplied target]
	Is(error) bool

	// Original returns the original error, i.e. without any of our wrappers
	// providing extra methods
	//
	// e.g.
	// er := errors.With(library.ErrSomeIssue).Extend("more text!")
	// og := er.Original()
	//
	// switch library.ErrSomeIssue {
	// case er:
	//     // we will never reach here
	// case og:
	//     // this is the original error!
	// }
	Original() error

	// Unwrap attempts to unwrap any internally wrapped errors
	//
	// e.g.
	// err1 := errors.BaseError("bad error oh noes")
	// err2 := err1.WrapWithin(library.ErrSomeIssue)
	//
	// if err2.Unwrap() == err1 {
	//     // this is true!
	// }
	Unwrap() error

	// Extend extends an error with extra information
	Extend(...interface{}) Error

	// Extendf extends an error with extra information using format strings
	Extendf(string, ...interface{}) Error

	// Wrap wraps the current error within a wrapper, using the originating
	// error-in-wrapper as the outer error
	Wrap(error) Error

	// WrapWithin wraps the originating error within a wrapper, using the
	// supplied error-in-wrapper as the outer error
	WrapWithin(error) Error
}