errors

As finds the first error in err's chain that matches target, and if so, sets target to that error value and returns true.

Code returns the http code for a error.

FormatError try to convert an error to *Error.

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

Unwrap returns the result of calling the Unwrap method on err, if err's type contains an Unwrap method returning error.

New returns an error object for the code, message.