Question: 
Write a function to calculate the number of digits and letters in a string.


Model's Code:
def dig_let(s):
    digits = sum(c.isdigit() for c in s)
    letters = sum(c.isalpha() for c in s)
    return (letters, digits)



Sample Correct Code:
def dig_let(s):
 d=l=0
 for c in s:
    if c.isdigit():
        d=d+1
    elif c.isalpha():
        l=l+1
    else:
        pass
 return (l,d)


Asserts:
assert dig_let("python")==(6,0)
assert dig_let("program")==(7,0)
assert dig_let("python3.0")==(6,2)


Tests:
Test 1 of 3: PASS
Test 2 of 3: PASS
Test 3 of 3: PASS

Test 343 of 974: 249/343 (72.59475218658892%): success