def respond_to?(method_name, include_private=false)
      return true if key?(method_name) || method_name.to_s.slice(/[=?!_]\Z/)
      super
    end
def respond_to?(method_name, include_private=false)
      return true if key?(method_name) || method_name.to_s.slice(/[=?!_]\Z/)
      super
    end
Will return true if the Mash has had a key
 set in addition to normal respond_to? functionality.