Suppose I have a string that matches /^(\~?.)*$/
and I want to split it into each atomic piece
that would be matched by (\~?.). How would I
code such a regular expression for split? I'd
like to use lookbehind, crafting an expression that says,
"Split after every non-tilde character", but my O'Reilly
Regular Expression book says that perl doesn't support
lookbehind. Any suggestions?