org-timestamp-format
org-timestamp-format is a compiled Lisp function in `org.el
'.
(org-timestamp-format TIMESTAMP FORMAT &optional END UTC)
Format a TIMESTAMP element into a string.
FORMAT is a format specifier to be passed to
`format-time-string'.
When optional argument END is non-nil, use end of date-range or
time-range, if possible.
When optional argument UTC is non-nil, time will be expressed as
Universal Time.