docs: def draw_lasers_3d(ax, lasers, name=None, distances=None, lim=None):
      """Draw MOT lasers in 3d."""
      if distances is None: distances = [1.0 for i in range(len(lasers))]
      for i in range(len(lasers)):
          if type(lasers[i]) == PlaneWave:
              draw_plane_wave_3d(ax, lasers[i], distances[i])
          elif type(lasers[i]) == MotField:
              draw_mot_field_3d(ax, lasers[i], distances[i])
  
      ax.set_xlabel(r"$x$", fontsize=20)
      ax.set_ylabel(r"$y$", fontsize=20)
      ax.set_zlabel(r"$z$", fontsize=20)
  
      if lim is None: lim = sqrt(2.0)
  
      ax.set_xlim(-lim, lim)
      ax.set_ylim(-lim, lim)
      ax.set_zlim(-lim, lim)
      ax.set_aspect("equal")
  
      if name is not None:
          pyplot.savefig(name, bbox_inches='tight')