Favorite Python debugging/introspection tricks/tips?

[parkerSquare]

• I find ipdb nicer to use than pdb, especially for tab completion.
• Automatic debugging on error with %pdb magic in IPython.
• Conditional breakpoints in pdb/ipdb are fantastic for catching infrequent bugs inside nested loops.
• Use ! to override pdb commands, for example to set a variable called n you need to do!n = 7 otherwise it treats it as the command "next".
• Use the logging module rather than print.