:sig
String to_upper(String s)

:params
s : the string to be converted
return value : returns a version of 's' where all lower case characters have been changed into upper case

:desc
Returns a upper case version of the input string 's'.

Note: this function is not yet Unicode-aware.

:see
>string

:related
**PHP:** `strtoupper()`
**JavaScript / Node.js:** `String.prototype.toUpperCase()`