def _error_on_bad_paths(fs, paths):
    for path in paths:
        if path == '-':
            return
        if fs.exists(path):
            return

    raise ValueError("At least one valid path is required. "
                     "None found in %s" % paths)
Raise an exception if there is not at least one valid path.
dataset/ETHPy150Open Yelp/mrjob/mrjob/sim.py/_error_on_bad_paths