[lindig]

Suggestion: parse any number like 12:03 as 12 minutes and 3 seconds (and 04:12:03 with hours) and represent it as seconds. It makes working with durations a lot easier. This is just an additional parsing rule (could also use 12m3 or 4h12m3) like 1e3 for 1*10^3 but is typically not implemented.

[dr_kretyn]

I'm reading 12m3 as "twelve cubic meters"