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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 mass_3d(self, r, kwargs, bool_list=None):
 """ computes the mass within a 3d sphere of radius r :param r: radius (in angular units) :param kwargs: list of keyword arguments of lens model parameters matching the lens model classes :param bool_list: list of bools that are part of the output :return: mass (in angular units, modulo epsilon_crit) """

        bool_list = self._bool_list(bool_list)
        mass_3d = 0
        for i, func in enumerate(self.func_list):
            if bool_list[i] is True:
                kwargs_i = {k:v for k, v in kwargs[i].items() if not k in ['center_x', 'center_y']}
                mass_3d_i = func.mass_3d_lens(r, **kwargs_i)
                mass_3d += mass_3d_i
                #except:
                #    raise ValueError('Lens profile %s does not support a 3d mass function!' % self.model_list[i])
        return mass_3d