title: Data structures: explanation of pop, push, dequeue, enqueue in this type of exercise
body: <p>I'm trying to become more comfortable with these 4 concepts.</p>
  
  <p>So if we had an array of <code>{15, 34, 23, 32, 15, 5}</code></p>
  
  <p>and we had operations such as</p>
  
  <pre><code>pop();
  push(30);
  enqueue(40);
  dequeue(100);
  </code></pre>
  
  <p>pop() would just remove the first number, which is 15, right ?
  what if it was pop(20) ?</p>
  
  <p>I'm assuming push(30) would add 30 as the last number.</p>
  
  <p>Do enqueue and dequeue work the same as pop and push? </p>
  
  <p>(Then would enqueue(40) add 40 at the back of the line? What would dequeue(100) do ?)</p>