public static ChannelBuilder create(String name){
  if (exists(name))   throw new IllegalArgumentException(String.format("Channel %s already exists",name));
  return new ChannelBuilder(name);
}

public static ChannelBuilder create ( String name ) { if ( exists ( name ) ) throw new IllegalArgumentException ( String . format ( "Channel %s already exists" , name ) ) ; return new ChannelBuilder ( name ) ; }
creates a new channel builder
