'Return byte count of disk space used by user or a human-readable
string if `nice_size` is `True`.'

def get_disk_usage(self, nice_size=False):

    rval = 0
    if (self.disk_usage is not None):
        rval = self.disk_usage
    if nice_size:
        rval = galaxy.util.nice_size(rval)
    return rval
