The `lc()` function turns each upper case character in the source string
into lower 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", [
		lc("This Will Be All Lowercased."),
		lc([ "An", "array", "ABC" ]),
		lc(123),
		lc(false),
		lc()
	]);
%}
-- End --

-- Expect stdout --
[
	"this will be all lowercased.",
	"[ \"an\", \"array\", \"abc\" ]",
	"123",
	"false",
	"null"
]
-- End --