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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 exner_function(pressure, reference_pressure=mpconsts.P0):
 r"""Calculate the Exner function. .. math:: \Pi = \left( \frac{p}{p_0} \right)^\kappa This can be used to calculate potential temperature from temperature (and visa-versa), since .. math:: \Pi = \frac{T}{\theta} Parameters pressure : `pint.Quantity` The total atmospheric pressure reference_pressure : `pint.Quantity`, optional The reference pressure against which to calculate the Exner function, defaults to P0 Returns ------- `pint.Quantity` The value of the Exner function at the given pressure See Also -------- potential_temperature temperature_from_potential_temperature """

    return (pressure / reference_pressure).to('dimensionless')**mpconsts.kappa