def with_channel(n = nil)
      ch = create_channel(n)
      begin
        yield ch
      ensure
        ch.close if ch.open?
      end

      self
    end
def with_channel(n = nil)
      ch = create_channel(n)
      begin
        yield ch
      ensure
        ch.close if ch.open?
      end

      self
    end
Creates a temporary {BunnyMock::Channel} instance, yields it to
 the block given, then closes it

 @param [Integer] n Channel identifier

 @return [BunnyMock::Session] self
 @api public