/// <summary>
/// This method requires a user id in order to get a list of courses that the student has completed.
/// </summary>
/// <param name="id">The id</param>
/// <returns>Returns the list of courses completed by the student.</returns>
public List <Course> coursesByStudent(int id)
{
QueryStrings queryStrings = new QueryStrings();
List <Course> coursesByStudent = queryStrings.getCouresesbyStudentId(id);
return(coursesByStudent);
}