**This Kata is intended as a small challenge for my students**
All Star Code Challenge #18
Create a function called that accepts 2 string arguments and returns an integer of the count of occurrences the 2nd argument is found in the first one.
If no occurrences can be found, a count of 0 should be returned.
Notes:
* The first argument can be an empty string  
* The second string argument will always be of length 1
def str_count(string, letter):
    return sum(map(lambda x: x == letter, string))
def str_count(string, letter):
    return sum(map(lambda x: x == letter, string))