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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def mixing_ratio(part_press, tot_press, molecular_weight_ratio=mpconsts.epsilon):
 r"""Calculate the mixing ratio of a gas. This calculates mixing ratio given its partial pressure and the total pressure of the air. There are no required units for the input arrays, other than that they have the same units. Parameters part_press : `pint.Quantity` Partial pressure of the constituent gas tot_press : `pint.Quantity` Total air pressure molecular_weight_ratio : `pint.Quantity` or float, optional The ratio of the molecular weight of the constituent gas to that assumed for air. Defaults to the ratio for water vapor to dry air (:math:`\epsilon\approx0.622`). Returns ------- `pint.Quantity` The (mass) mixing ratio, dimensionless (e.g. Kg/Kg or g/g) Notes ----- This function is a straightforward implementation of the equation given in many places, such as [Hobbs1977]_ pg.73: .. math:: r = \epsilon \frac{e}{p - e} See Also -------- saturation_mixing_ratio, vapor_pressure """

    return (molecular_weight_ratio * part_press
            / (tot_press - part_press)).to('dimensionless')