问如何将行的三元组简单地排序到列中，并避免对行的双元组执行这种操作？

EN

with open('input_file.txt', 'r') as input_file:
    with open('output_file.txt', 'w') as output_file:
        non_empty = 0
        previous_lines = []
        for line in input_file.readlines():
            if line == '\n':
                if non_empty == 3:  # found a triple
                    output_file.write(' '.join(previous_lines) + '\n')
                # if it's not a triple, just ignore it
                # reset the counter so we can detect the next triple
                non_empty = 0
                previous_lines = []
            else:
                # record a non-empty line for later use
                previous_lines.append(line.replace('\n', ''))
                # and important: count how many non-empty lines there are
                non_empty += 1