[Python] DimensionalityError when calculating an exponential value "exp(x)" with pint units

I am trying to calculate an exponential value exp with a python pint variable that includes a unit.

import pint
var = 0.5 * unit_reg.minute
math.exp(-var)


with this I get the error: DimensionalityError: Cannot convert from 'minute' to 'dimensionless'

This also seems the case when I calculate it directly

import pint
var = 0.5 * unit_reg.minute
math.e ** -var


as well as use numpy

import pint
import numpy as np
var = 0.5 * unit_reg.minute
np.exp(-var)


Maybe I am missing something here. But is there another way of doing the calculations rather than extracting the magnitude and units from the variable and set things together again?

With this way there is no DimensionalityError

import pint
var = 0.5 * unit_reg.minute
math.exp(-var.magnitude) * var.units


I am guessing, that math.exp is expecting a dimensionless variable as specified in example 11 on the pint numpy description

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