Takes a Unicode character code (as an integer), and returns the Unicode character as a string.
This function can work for ASCII conversions as well, since Unicode and ASCII character codes match for all ASCII characters.
Integer code - The character code for a Unicode character.
String - The corresponding Unicode character, as a one-character string.
char(88) //Returns "X".
char(425) //Returns "?".
char(-1) //Returns Error_Expression Eval.