code: def masses_of_galaxies_within_circles_in_units(self, radius : dim.Length, unit_mass='angular',
                                                     critical_surface_density=None):
          
          return list(map(lambda galaxy: galaxy.mass_within_circle_in_units(
                          radius=radius, unit_mass=unit_mass, kpc_per_arcsec=self.kpc_per_arcsec,
                          critical_surface_density=critical_surface_density),
                          self.galaxies))
docs: Compute the total mass of all galaxies in this plane within a circle of specified radius.
  
          See *galaxy.angular_mass_within_circle* and *mass_profiles.angular_mass_within_circle* for details
          of how this is performed.
  
          Parameters
          ----------
          radius : float
              The radius of the circle to compute the dimensionless mass within.
          units_mass : str
              The units the mass is returned in (angular | solMass).
          critical_surface_density : float
              The critical surface mass density of the strong lens configuration, which converts mass from angulalr \
              units to physical units (e.g. solar masses).