static getFunctionContent(fn) {
		return fn
			.toString()
			.replace(FUNCTION_CONTENT_REGEX, "")
			.replace(INDENT_MULTILINE_REGEX, "")
			.replace(LINE_SEPARATOR_REGEX, "\n");
	}
@template {EXPECTED_FUNCTION} T
@param {T} fn a runtime function (.runtime.js) "template"
@returns {string} the updated and normalized function string