The python debugger
pdb2.7 script [...]
See /usr/lib/python2.7/pdb.doc for more information on the use of pdb. When the debugger is started, help is available via the help command.
python2.7(1). Chapter 9 of the Python Library Reference (The Python Debugger). Available in the python2.7-doc package at /usr/share/doc/python2.7/html/lib/module-pdb.html.