lookup = function (type) {
			var standardFunction = AEL.ExpressionFunctions.standardFunctions.get(type);
			if (standardFunction) {
				return standardFunction;
			}
			else {
				return new AEL.ExpressionEvaluator(type, function (expression, state, options) { throw new Error("Unknown function " + type); }, AEL.ReturnType.String);
			}
		}
Parses an interpolated string into an Expression object ready to evaluate.

@param interpolatedString The interpolated string to parse. Example: "Hello ${name}"
@returns An Expression object if the provided interpolated string contained at least one expression (e.g. "${expression}"); the original string otherwise.