code: func Xargs(command string, args ...string) *XargsFilter {
  	// Compute length of command+args
  	base := len(command)
  	for _, a := range args {
  		base += 1 + len(a)
  	}
  	return &XargsFilter{
  		command:    command,
  		args:       args,
  		limitArgs:  4096,
  		limitBytes: 4096 - 100 - base, // Posix limit with slop
  	}
  }
docs: // Xargs returns a filter that executes "command args... items..."
  // where items are the input to the filter.  The handling of items may
  // be split across multiple executions of command (typically to meet
  // command line length restrictions).  The standard output of the
  // execution(s) is split into lines and the lines form the output of
  // the filter (with trailing newlines removed).