classlist.py

from argparse import ArgumentParser

parser = ArgumentParser()

parser.add_argument('--students', required=True, help='A file containing student information')
parser.add_argument('--display', nargs='+')

arguments = parser.parse_args()

students = list()

with open(arguments.students) as student_file:
    for line in student_file:
        line = line.strip()
        parts = line.split(",")

        student = dict()
        student["id"] = int(parts[0])
        student["first"] = parts[1]
        student["last"] = parts[2]
        student["email"] = parts[3]

        students.append (student)

if arguments.display:
    students_to_display = arguments.display
else:
    students_to_display = list()
    id=int(input('Enter the id of the desired student: '))
    students_to_display.append(id)

for id in students_to_display:
    for student in students:
        if student['id'] == int(id):
            print ("{} {} ({})".format(student['first'], student['last'], student['email']))
            break