Example illustrating some capabilities of the subpackage lensing. Left panel: eight lens profiles with different parameters are combined to generate a complex mass distribution. The total surface mass density is shown in tones of gray and dashed curves highlight few particular iso-density contours. The colored thick curves show the critical curves and the filled and empty markers locate the lensed image positions of two different sources shown in the right panel. The inverted triangles correspond to images of type I (maximum of τ), the diamonds to type II (saddle point of τ), and triangles to type III (maximum of τ). The size of the markers is log-proportional to the magnification of the images. Right panel: the colored lines show the caustics and the two squares locate the sources. The filled (resp. empty) square has seven (resp. nine) images, all shown in the left panel. The axis scale is arcseconds but unit of θ_E can also be used.