Question: 
Write a function to find the occurence of characters 'std' in the given string 1. list item 1. list item 1. list item 2. list item 2. list item 2. list item


Model's Code:
def count_occurance(s):
    return s.count('std')



Sample Correct Code:
def count_occurance(s):
  count=0
  for i in range(len(s)):
    if (s[i]== 's' and s[i+1]=='t' and s[i+2]== 'd'):
      count = count + 1
  return count


Asserts:
assert count_occurance("letstdlenstdporstd") == 3
assert count_occurance("truststdsolensporsd") == 1
assert count_occurance("makestdsostdworthit") == 2


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

Test 172 of 974: 127/172 (73.83720930232558%): success