human
I wrote the below code

    listing = zfs_command(reactor, ['list', '-d', '1', '-H', '-p', '-o', 'name,mountpoint,refquota', pool])
    def listed(output, pool):
        for line in output.splitlines():
            (name, mountpoint, refquota) = line.split(' DCTB ')
            name = name[(len(pool) + 1):]
            if name:
                refquota = int(refquota.decode('ascii'))
                if (refquota == 0):
                    refquota = None
                (yield _DatasetInfo(dataset=name, mountpoint=mountpoint, refquota=refquota))
    listing.addCallback(listed, pool)
    return listing

What's a good function header?
assistant
#Here's a good function header.

def _list_filesystems(reactor, pool):