function getUpdateDirection(update, counter) {
			if (
				update.argument.type === "Identifier" &&
				update.argument.name === counter
			) {
				if (update.operator === "++") {
					return 1;
				}
				if (update.operator === "--") {
					return -1;
				}
			}
			return 0;
		}
check UpdateExpression add/sub the counter
@param {ASTNode} update UpdateExpression to check
@param {string} counter variable name to check
@returns {number} if add return 1, if sub return -1, if nochange, return 0