def mass_in_theta_E(self, theta_E):
        """
        mass within Einstein radius (area * epsilon crit) [M_sun]
        :param theta_E: Einstein radius [arcsec]
        :return: mass within Einstein radius [M_sun]
        """
        mass = self.arcsec2phys_lens(theta_E) ** 2 * np.pi * self.epsilon_crit
        return mass
def mass_in_theta_E ( self , theta_E ) : mass = self . arcsec2phys_lens ( theta_E ) ** 2 * np . pi * self . epsilon_crit return mass
mass within Einstein radius (area * epsilon crit) [M_sun]
        :param theta_E: Einstein radius [arcsec]
        :return: mass within Einstein radius [M_sun]