def vol(self, bias: bool=False, *args, **kwargs):
    warnings.warn('vol is deprecated will be removed in a future version. Use std instead.', FutureWarning, stacklevel=2)
    return self.std(bias, *args, **kwargs)
def vol(self, bias: bool=False, *args, **kwargs):
    warnings.warn('vol is deprecated will be removed in a future version. Use std instead.', FutureWarning, stacklevel=2)
    return self.std(bias, *args, **kwargs)