import collections


def read_gathered_las(path):
    """Return dict of block->[las_paths].
    For now, these are ws separated on each line of input.
    """
    result = collections.defaultdict(list)
    with open(path) as ifs:
        for line in ifs:
            block, las_path = line.split()
            result[int(block)].append(las_path)
    # LOG.warning('path={!r}, result={}'.format(
    #    path, pprint.pformat(result)))
    return result