func (c Commands) Alias(command string, alias string) error {
	cmd, ok := c[command]
	if !ok {
		return ErrInvalidCommand
	}
	c[alias] = cmd
	return nil
}
Alias will add another command for the same handler, won't get added to help.
package chat
import (
	"errors"
	"fmt"
	"sort"
	"strings"
	"time"
	"github.com/shazow/ssh-chat/chat/message"
	"github.com/shazow/ssh-chat/internal/sanitize"
	"github.com/shazow/ssh-chat/set"
)
var ErrInvalidCommand = errors.New("invalid command")
var ErrNoOwner = errors.New("command without owner")
var ErrMissingArg = errors.New("missing argument")
var ErrMissingPrefix = errors.New("command missing prefix")
type Command struct {
	Prefix     string  
	PrefixHelp string  
	Help       string  
	Op         bool    
	Handler func(*Room, message.CommandMsg) error
}
type Commands map[string]*Command
func (c Commands) Add(cmd Command) error {
	if cmd.Prefix == "" {
		return ErrMissingPrefix
	}
	c[cmd.Prefix] = &cmd
	return nil
}