code: func Trace(msg string, ctx ...interface{}) {
  	root.write(msg, LvlTrace, ctx, skipLevel)
  }
docs: // The following functions bypass the exported logger methods (logger.Debug,
  // etc.) to keep the call depth the same for all paths to logger.write so
  // runtime.Caller(2) always refers to the call site in client code.
  // Trace is a convenient alias for Root().Trace