Question: 
Write a python function to count number of non-empty substrings of a given string.


Model's Code:
def number_of_substrings(s):
    n = len(s)
    return n * (n + 1) // 2



Sample Correct Code:
def number_of_substrings(str): 
	str_len = len(str); 
	return int(str_len * (str_len + 1) / 2); 


Asserts:
assert number_of_substrings("abc") == 6
assert number_of_substrings("abcd") == 10
assert number_of_substrings("abcde") == 15


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

Test 238 of 974: 172/238 (72.26890756302521%): success