CheckErr prints a user-friendly error to STDERR and exits with a non-zero exit code.

DefaultSubCommandRun prints a command's help string to the specified output if no arguments (sub-commands) are provided, or a usage error otherwise.

MultilineError returns a string representing an error that splits sub errors into their own lines.

MultipleErrors returns a newline delimited string containing the prefix and referenced errors in standard form.

RequireNoArguments exits with a usage error if extra arguments are provided.

StandardErrorMessage translates common errors into a human readable message, or returns false if the error is not one of the recognized types.

UsageErrorf returns error with command path.

DefaultErrorExitCode defines the default exit code.

ErrExit may be passed to CheckError to instruct it to output nothing but exit with status code 1.