Python handles runtime errors with exceptions. This debugging post shows a Python 2.x trap where missing parentheses in an except clause can overwrite an exception name and make later exception handling behave incorrectly.
Regular expressions are popular among many programmers. This debugging article looks at what is wrong with the expression [+-0123456789] and why a minus sign inside a character class can change the whole meaning.
This debugging note only touches Python indirectly, but a Python Tornado server plays the main role. It describes a problem with proxying WebSockets through Apache and why HTTP subpaths had to be proxied explicitly before the WebSocket path.
Where did the bug probably happen? This typical debugging question opens a short series about Python bugs that look obvious only after they are found. The first example shows how a missing comma in a multiline tuple or list literal can lead to surprising behaviour.