The `uc()` function turns each lower case character in the source string
into upper case and returns the resulting copy.

The input argument is converted to a string in case it is not already a
string value.

-- Testcase --
{%
	printf("%.J\n", [
		uc("This Will Be All Uppercased."),
		uc([ "An", "array", "ABC" ]),
		uc(123),
		uc(false),
		uc()
	]);
%}
-- End --

-- Expect stdout --
[
	"THIS WILL BE ALL UPPERCASED.",
	"[ \"AN\", \"ARRAY\", \"ABC\" ]",
	"123",
	"FALSE",
	"NULL"
]
-- End --