SUBSTRING
=========

syntax: (substring <string> <start> [<end>])

This function creates a string, which is part of the
<string>. The character of the start-position is
included. The character of the end-position is not
included. SUBSTRING does not exist in Common-Lisp.
In Common Lisp you can use the command SUBSEQ.

example:       >(substring "abcd" 1 2)
               "b"
               >(substring "abcd" 2)
               "cd"