how to make a grading system in python

1def determine_grade(scores):
2    if scores >= 90 and <= 100:
3        return 'A'
4    elif scores >= 80 and <= 89:
5        return 'B'
6    elif scores >= 70 and <= 79:
7        return 'C'
8    elif scores >= 60 and <= 69:
9        return 'D'
10    elif scores >= 50 and <= 59:
11        return 'E'
12    else:
13        return 'F'
14