def underbang_reader(key)
      ck = convert_key(key)
      if key?(ck)
        regular_reader(ck)
      else
        self.class.new
      end
    end
def underbang_reader(key)
      ck = convert_key(key)
      if key?(ck)
        regular_reader(ck)
      else
        self.class.new
      end
    end
This is the under bang method reader, it will return a temporary new Mash
 if there isn't a value already assigned to the key requested.