Return a ChannelPack instance loaded with dbf data file fn.

    This is a lazy function to get a loaded instance, using pulldbf
    module.

def dbfpack(fn, usecols=None):
    """Return a ChannelPack instance loaded with dbf data file fn.

    This is a lazy function to get a loaded instance, using pulldbf
    module."""

    loadfunc = pulldbf.dbf_asdict
    cp = ChannelPack(loadfunc)
    cp.load(fn, usecols)
    names = pulldbf.channel_names(fn, usecols)
    cp.set_channel_names(names)
    # cp.set_basefilemtime()
    return cp