Add Look Up Time Zone Info For Identifier as a Rails TIL

rails/look-up-time-zone-info-for-identifier.md

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+# Look Up Time Zone Info For Identifier
+
+The `ActiveSupport::TimeZone` class overrides the `#[]` method to be a lookup
+mechanism for IANA Time Zone Identifier strings. These are strings like
+`America/Chicago` (or anything else listed under `TZInfo::Timezone.all`).
+
+Let's get an instance for `America/Chicago`.
+
+```ruby
+> chi = ActiveSupport::TimeZone['America/Chicago']
+=> #<ActiveSupport::TimeZone:0x00000001099d8140
+ @name="America/Chicago",
+ @tzinfo=#<TZInfo::DataTimezone: America/Chicago>,
+ @utc_offset=nil>
+```
+
+Notice it has a `tzinfo` instance variable that we can access. That object
+contains all kinds of useful things.
+
+```ruby
+> chi.tzinfo.name
+=> "America/Chicago"
+> chi.tzinfo.friendly_identifier
+=> "America - Chicago"
+> chi.tzinfo.abbr
+=> "CDT"
+> chi.tzinfo.utc_offset
+=> -18000
+> chi.tzinfo.dst?
+=> true
+```
+
+All of these and more. Run `ls chi.tzinfo` in a `pry` session to see what else.