def include_class?( writer_class )
      @writers.keys.each do | writer_instance |
        return true if writer_instance.is_a?( writer_class )
      end

      return false
    end
def include_class?( writer_class )
      @writers.keys.each do | writer_instance |
        return true if writer_instance.is_a?( writer_class )
      end

      return false
    end
Does this log instance's collection of writers include any writer
 instances which are of the given writer _class_? Returns +true+ if so,
 else +false+.

 This is slower than #include? so try to work with writer instance
 queries rather than writer class queries if you can.

 +writer_class+:: A _subclass_ (class reference, not instance) of
                  Hoodoo::Logger::FastWriter or
                  Hoodoo::Logger::SlowWriter.