Sometimes I use regular expressions to do some mass text processing. Today I was working on a first version of my Python glossary and wanted to reformat a couple of things. In the process, I wanted to move some words around and one of the words would now become the first word in a new paragraph, so it needed to be turned into an uppercase letter.
I knew I could do this with regular expressions so I googled how to do it and this Stack Overflow answer was what I was looking for.
The sequences \l, \L, \u, and \U, can be used to modify the casing of the groups that are included after.
For example, using the search pattern (\w+) and the replace pattern \u$1 on the text "bananas" will replace it with "Bananas".
Using \U instead will convert all letters to uppercase instead of just the first one.