func IsRuntimeError(err error) bool {
	_, ok := err.(*runtimeError)
	return ok
}
IsRuntimeError returns if the supplied error was a runtime error as opposed to an error arising out of user input.
package cmd
import "errors"
type usageError struct {
	error
}
func NewUsageError(msg string) error {
	return &usageError{
		error: errors.New(msg),
	}
}
func IsUsageError(err error) bool {
	_, ok := err.(*usageError)
	return ok
}
type runtimeError struct {
	error
}
func NewRuntimeError(err error) error {
	return &runtimeError{
		error: err,
	}
}
func (e *runtimeError) Unwrap() error {
	return e.error
}