Somewhere in my head is a very specialised pattern-recognition neuron, which seems to fire whenever I encounter – or, even more so, inadvertently write – any phrase or sentence that would scan perfectly as the first line of a limerick.

It's a very persistent and attention-grabbing neuron, for some reason. Every time it fires, I have to spend the next half hour vigorously resisting the urge to try to come up with the rest of the limerick. Even if the triggering phrase is something utterly, tediously mundane, as for example the one that emerged from my fingers just now as a hasty commit message: ‘A cleanup I noticed in passing’.