<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def timeit(hosts=None, stmt=None, warmup=30, repeat=None, duration=None, concurrency=1, output_fmt=None, fail_if=None, sample_mode='reservoir'):
 """Run the given statement a number of times and return the runtime stats Args: fail-if: An expression that causes cr8 to exit with a failure if it evaluates to true. The expression can contain formatting expressions for: - runtime_stats - statement - meta - concurrency - bulk_size For example: --fail-if "{runtime_stats.mean} > 1.34" """

    num_lines = 0
    log = Logger(output_fmt)
    with Runner(hosts, concurrency, sample_mode) as runner:
        version_info = aio.run(runner.client.get_server_version)
        for line in as_statements(lines_from_stdin(stmt)):
            runner.warmup(line, warmup)
            timed_stats = runner.run(line, iterations=repeat, duration=duration)
            r = Result(
                version_info=version_info,
                statement=line,
                timed_stats=timed_stats,
                concurrency=concurrency
            )
            log.result(r)
            if fail_if:
                eval_fail_if(fail_if, r)
        num_lines += 1
    if num_lines == 0:
        raise SystemExit(
            'No SQL statements provided. Use --stmt or provide statements via stdin')