def matcher(key, value)
      if value.is_a?(Hash)
        name = "Mongoid::Matchers::#{value.keys.first.gsub("$", "").camelize}"
        return name.constantize.new(send(key))
      end
      Mongoid::Matchers::Default.new(send(key))
    end
def matcher(key, value)
      if value.is_a?(Hash)
        name = "Mongoid::Matchers::#{value.keys.first.gsub("$", "").camelize}"
        return name.constantize.new(send(key))
      end
      Mongoid::Matchers::Default.new(send(key))
    end
Get the matcher for the supplied key and value. Will determine the class
 name from the key.