Vim plugin that lets you extend the behaviour of the ~ key.
In vanilla Vim, the ~ key is used to switch the case of either the character
under the cursor or the visually selected text. Similarly, g~ is an operator
to switch the case of characters over a text object or motion.
Using this plugin, you can define new pairs of alternative characters. For
example, you can make - be switched to _ and _ be switched to - with
the ~ key.
Check out the documentation for more.