def write(file_name, file_contents, data)
      fname = cache_file_name(file_name, file_contents)
      @previous_entry = fname
      File.open(fname, "wb") {|file| Marshal::dump(data, file) }
    end
def write(file_name, file_contents, data)
      fname = cache_file_name(file_name, file_contents)
      @previous_entry = fname
      File.open(fname, "wb") {|file| Marshal::dump(data, file) }
    end
Writes parse data into cache under a name generated from the
 name and contents of a source file.