func (c *Client) Command(format string, args ...interface{}) *Command {
	for i := range args {
		switch s := args[i].(type) {
		case Quoted:  
		case string:
			args[i] = quote(s)
		}
	}
	return &Command{
		client: c,
		cmd:    fmt.Sprintf(format, args...),
	}
}
Command returns a command that can be sent to MPD sever.
It enables low-level access to MPD protocol and should be avoided if
the user is not familiar with MPD protocol.

Strings in args are automatically quoted so that spaces are preserved.
Pass strings as Quoted type if this is not desired.
package mpd
import "fmt"
type Quoted string