differentiation of dimensionless fractions

[3mrrrx]

it would be very helpful if there is way to differentiate between different dimensionless fractions; e.g. resulting a mass fraction (dimensionality: [mass]/[mass]) and volume fraction (dimensionality: [vol]/[vol], with vol =[m] **3).

so far, I have tried different approaches using pint, but these all lead to a total loss of dimensionality; e.g. by defining a new unit with null/trivial dimensionality:

[massFraction] = [mass] ** 0

[volFraction] = [vol] ** 0

kindly help me find the best approach to this problem using pint, as it will help avoid error resulting of comparing vol and mass fractions.