Code for Greatest Common Divisor in Python
<p>The Question</p>

<blockquote>
  <p>The greatest common divisor (GCD) of a and b is the largest number
  that divides both of them with no remainder.</p>
  
  <p>One way to find the GCD of two numbers is Euclid’s algorithm, which is
  based on the observation that if r is the remainder when a is divided
  by b, then gcd(a, b) = gcd(b, r). As a base case, we can use gcd(a, 0)
  = a.</p>
  
  <p>Write a function called gcd that takes parameters a and b and returns
  their greatest common divisor.</p>
</blockquote>

<p>This in my opinion, may be useful, so I just wanted to put an answer in case anyone needs it. </p>
