def log2_normalize(self, prepend_cols=None, append_cols=None, *args, **kwargs):
    """Return a Log2 normalized DataFrame Log2(values)-mean(Log2(values))."""

    result = self.log2().sub(self.log2().mean(axis=1), axis=0)

    if prepend_cols:
        result.columns = prepend_cols + result.columns

    if append_cols:
        result.columns = result.columns + append_cols

    return result