fn.substring( $sourceString as String?, $startingLoc as Number, [$length as Number] ) as String?
Returns a substring starting from the $startingLoc and continuing for $length characters.
|$sourceString||The string from which to create a substring.|
|$startingLoc||The number of characters from the start of the $sourceString.|
|$length||The number of characters beyond the $startingLoc.|
fn.substring("123456", 2, 2); => "23"