title: Convert from local time to GMT (World Clock application using nodatime)
body: <p>I am trying to program a world clock using Nodatime, and I have searched the web for samples on how to use the library and I have read the documentation, and it says that the class Instant is simply a number of "ticks" since some arbitrary epoch the Unix epoch, which corresponds to midnight on January 1st 1970 UTC. Well, I empirically guessed that if I used as an Instant a GMT value, then I could calculate with it the time values for each time zone (creating the world clock), and it worked. The problem that I have, is that I don't know a simple way to calculate the GMT time (or GMT instant) from the local time, my time zone is "America/Mexico_City", so my question is, is there a shortcut already defined in Nodatime to get the GMT time from a local time, or in the other hand, is there a simple way to implement the "Instant GetInstantGMT()" function (the function has to take in count the day light saving time issues)?    </p>