This doesn't fix my concern. The default is still `local` and that is a problem. Taking this conscious explicit choice away from the developer is a bad idea.

i would prefer something like: ```nim type TimesTypes = DateTime | Time | Duration | TimeInterval proc `+=`*[T: TimesTypes, U](a: var T, b: U) = a = a + b proc `-=`*[T: TimesTypes, U](a: var T, b: U) = a = a - b proc `*=`*[T: TimesTypes, U](a: var T, b: U) = a = a * b ```

sorry i forgot to tell you, that this assertion will become false, if you apply my fix for the negative nanoseconds. ``` $initDuration(milliseconds=-1500) == "-2 seconds and 500 milliseconds" ``` if nanoseconds are forced to be always positive

this should be: ```nim if remNS < 0: ```

Sorry, but please remove these. These should be put into ``system`` but for that we need a separate PR (if you could create that then I would be eternally grateful 😀)

Is it ever useful to do so? If not then it should just be disallowed outright.

Docs are important :) Maybe something like this: ```nim ## Converts a duration into an array consisting of fixed time units. ## ## Each value in the array gives information about a specific unit of ## time, for example ``result[Days]`` gives a count of days. ## ## This procedure is useful for converting ``Duration`` values to strings. ```

Please remove these comments, they might end up in the doc gen. They also don't really add much except noise. One comment is enough.

You forgot to update the comment, it should just warn that `a + between(a, b) == b` is only guaranteed when `a` and `b` are in UTC.

Same as I've written above. Remove this function.

> use the format from ``format(dt: DateTime, f: string)``. Huh? I don't understand this.

Why do we need this when we have ``-`` which produces a ``Duration``?

Please don't abuse runnableExamples for tests. What you have here is far too much.

``` **Warning:** ```

These kinds of operators shouldn't be defined, we need a template that does this for every type that defines a ``+``, ``-``, ``*``, etc. Otherwise defining these all the time is a PITA. I feel like I've mentioned this somewhere else but of course GitHub's search fails when searching for \`+=\` -.-

We need another proc that's a bit less granular than this proc as well. Something that will work on the Nim Forum for example: https://forum.nim-lang.org/ ("26 minutes ago", "2 hours ago").

The ``DurationParts`` type is not exported above, that's bad. I'm also wondering what these duration parts are. The documentation for this functions needs to explain this better. (Based on the procs below I have a feeling this proc is perhaps not supposed to be exported?)

Maybe to add ```milliseconds``` and ```microseconds```?

Maybe change the order of the parameters? To ```proc initDuration*(weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds: int64 = 0): Duration``` For compatibility with ```initDateTime```.