The Python is Colt's famous .357 Magnum revolver, brought back into production in recent years. EGW makes a red dot mount that fits it without drilling or machining.
The mount
Swapped in for the rear sight, it holds RMR pattern dots of any make.
Why a dot on a Python
A dot gives a single aiming point for target and hunting use and helps eyes that struggle with iron sights.
Shared
The same mount is listed for the Anaconda and Trooper Mark 3.