! is called the Fabulous Operator in z^3 languate. In the basic form, it is meant to compute the fantastic factorial function. However, based on the arguments provided, it can simply create powerful functions with the simple notation of ! to a string, regular expression, etc. This dramatically simplifies notation to create functions, and makes for powerful and fabulously expressive code.
! Operator can have multiple meanings, when used as a suffix. of course, as a prefix, ! represents NOT as in most C like languages.
! can be used to (1) Compute factorial of numbers (including complex numbers etc), (2) Create functions out of strings, (3) Create predicate functions and search functions out of simple notations with regular expressions, strings, etc.