python  What does this string mean in the program? I need an understanding of its function and how it plays a big piece in the program. what does the line, strip, and split also do?  for line in myGrades_file: mycourses, grades = line.strip().split(',')   line from this program  def create(): myGrades_file = open('grades.txt', 'w') while True: my_courses = input("Enter course name or Enter to quit: ") if my_courses == '': print("File was created and closed") break my_grades = int(input("Enter grade (integer) achieved: ")) myGrades_file.write(my_courses) myGrades_file.write(str(my_grades) + '\n') myGrades_file.close() return True def retrieve(): print("\nHere are your grades:") myGrades_file = open('grades.txt', 'r') grades_total = 0 count = 0 gpa = 0 line = myGrades_file.readline() for line in myGrades_file: mycourses, grades = line.strip().split(',') grades_total += int(grades) if (int(grades) >= 90): gpa += 4.0 elif (int(grades) >= 80): gpa += 3.0 elif (int(grades) >= 70): gpa += 2.0 elif (int(grades) >= 60): gpa += 1.0 else: gpa += 0.0 count += 1 gpa_total = gpa / count print("{} score is {}".format(mycourses, grades)) average = grades_total / count print("Average grade among your courses is {:.2f}".format(average), "Your GPA is {:.2f}".format(gpa_total)) return average def main(): create() average = retrieve() main()

python 

What does this string mean in the program? I need an understanding of its function and how it plays a big piece in the program. what does the line, strip, and split also do? 

for line in myGrades_file:
mycourses, grades = line.strip().split(',')

line from this program 

def create():
myGrades_file = open('grades.txt', 'w')
while True:
my_courses = input("Enter course name or Enter to quit: ")
if my_courses == '':
print("File was created and closed")
break
my_grades = int(input("Enter grade (integer) achieved: "))
myGrades_file.write(my_courses)
myGrades_file.write(str(my_grades) + '\n')

myGrades_file.close()
return True

def retrieve():
print("\nHere are your grades:")

myGrades_file = open('grades.txt', 'r')
grades_total = 0
count = 0
gpa = 0
line = myGrades_file.readline()

for line in myGrades_file:
mycourses, grades = line.strip().split(',')

grades_total += int(grades)
if (int(grades) >= 90):
gpa += 4.0
elif (int(grades) >= 80):
gpa += 3.0
elif (int(grades) >= 70):
gpa += 2.0
elif (int(grades) >= 60):
gpa += 1.0
else:
gpa += 0.0
count += 1
gpa_total = gpa / count

print("{} score is {}".format(mycourses, grades))

average = grades_total / count

print("Average grade among your courses is {:.2f}".format(average), "Your GPA is {:.2f}".format(gpa_total))

return average

def main():
create()
average = retrieve()

main()