how can i count the number of times a certain string occurs in a variable? : <p>im just learning how to program on edx, and theres this question that i just can seem to understand not to even talk of solving. please i need solutions and idea on  how to understand the question and implement it</p>

<ul>
<li>QUESTION-</li>
</ul>

<p>Assume s is a string of lower case characters.</p>

<p>Write a program that prints the number of times the string 'bob' occurs in s. For example, if s = 'azcbobobegghakl', then your program should print</p>

<p>Number of times bob occurs is: 2</p>
