k (Optional) A string representing a valid locale. If you do not include a value for k, the ambient locale is used.
Note: This function only converts the Unicode characters U+61 through U+7A (of the ASCII character set) as well as the characters U+FF41 through U+FF5A (of the fullwidth character set).The following expressions are examples of using the Upper function:
This example converts the first occurrence of Address to all uppercase letters.