Create a public class named Course. Course should define a single public constructor that accepts three fields: a String (the department), a String (the course number, and yes, this must be a String) and an int (the enrollment). You are welcome to name these fields however you like! Your constructor should reject null departments and numbers and negative enrollments.

You do not need to provide any getters and setters! Instead, define a single method named equals. Your equals method accepts an Object as a single parameter. It should return true if the passed object is a Course and has the same values for the department and number, and false otherwise.