Erros comuns em Python

O Mark Lutz, autor do excelente Learning Python e professor de Python, publicou um artigo no ONLamp.com sobre os erros mais frequentes dos programadores de Python.

Já cometi pelo menos um dos erros mencionados mais do que uma vez:

Imports Only Work the First Time:
You can run a file by importing it at the interactive prompt, but this only works once per session; subsequent imports simply return the already-loaded module. To force Python to reload and rerun a file's code, call the reload(module) function instead. And while you're at it, be sure to use parentheses for reload, but not import.

Igualmente importante:

reload doesn't impact names copied with from: reload works much better with the import statement. If you use from statements, remember to rerun the from after the reload, or you'll still have old names.