• OpenCV =>3.4.3 / 3.4.4
• Operating System / Platform => Windows 64 Bit / ubuntu 16
• Compiler => opencv-contrib-python 3.4.4 / 3.4.3 (from pip)

for unknown reason, sample only runs,
if we use cv.reg_MapShift cv.reg_MapperGradShift and cv.reg_MapperPyramid here:

(underscores instead of dots)
(easy to fix, but the underscores look quite weird to me)

it also segfaults, if it used like this:

 mappPyr = cv.reg_MapperPyramid(cv.reg_MapperGradShift()) 

instead of:

 mapper = cv.reg_MapperGradShift() 
 mappPyr = cv.reg_MapperPyramid(mapper)