Python has a debugger , which is available as a module called pdb . It supports setting conditional breakpoints , stepping through the source code one line at a time, stack inspection, and more.

import pdb
msg = "this is a test"
pdb.set_trace()
print(msg)

Insert pdb.set_trace() anywhere and it will function as a breakpoint . When you execute the script by python test.py, you will in the python debug mode.