How to use the keyvi.KeyOnlyDictionaryCompiler function in keyvi

def compile(args):
    params = {key: value for key, value in args.compiler_params}

    dict_type = args.dict_type
    if dict_type == 'json':
        dictionary = keyvi.JsonDictionaryCompiler(params)
    elif dict_type == 'string':
        dictionary = keyvi.StringDictionaryCompiler(params)
    elif dict_type == 'int':
        dictionary = keyvi.IntDictionaryCompiler(params)
    elif dict_type == 'completion':
        dictionary = keyvi.CompletionDictionaryCompiler(params)
    elif dict_type == 'key-only':
        dictionary = keyvi.KeyOnlyDictionaryCompiler(params)
    else:
        return 'Must never reach here'

    with open(args.input_file) as file_in:
        for line in file_in:
            line = line.rstrip('\n')
            try:
                splits = line.split('\t')
                if dict_type == 'key-only':
                    dictionary.Add(splits[0])
                elif dict_type == 'int' or dict_type == 'completion':
                    dictionary.Add(splits[0], int(splits[1]))
                else:
                    dictionary.Add(splits[0], splits[1])
            except:
                print ('Can not parse line: {}'.format(line))