this allows using a slice operator alongside other (special) format
specifiers like J, to first join list elements to a string and then
trimming that with a slice.
{tags:J, /[:50]}
To be able to parse any string into a 'datetime' object
and format it as necessary.
Example:
{created_at:D%Y-%m-%dT%H:%M:%S%z}
->
"2010-01-01 00:00:00"
{created_at:D%Y-%m-%dT%H:%M:%S%z/%b %d %Y %I:%M %p}
->
"Jan 01 2010 12:00 AM"
with 'created_at' == "2010-01-01T01:00:00+0100"
