Package log implements a simple logging package. It defines a type, Logger, with methods for formatting output. It also has a predefined ‘standard’ Logger accessible through helper functions Print[f|ln], Fatal[f|ln], and Panic[f|ln], which are easier to use than creating a Logger manually. That logger writes to standard error and prints the date and time of each logged message. Every log message is output on a separate line: if the message being printed does not end in a newline, the logger will add one. The Fatal functions call os.Exit(1) after writing the log message. The Panic functions call panic after writing the log message.
func Fatal(v ...interface{})
Fatal is equivalent to Print() followed by a call to os.Exit(1).
// Fatal is equivalent to Print() followed by a call to os.Exit(1).
func Fatal(v ...interface{}) {
std.Output(2, fmt.Sprint(v...))
os.Exit(1)
}