title: How to add a letter after every letter in a string?
body: <p>I want to create an encryption script that encrypts the string given to it, here's how it went.</p>
  <pre class="lang-py prettyprint-override"><code># First, I created a list of the string I got
  string = '16271'
  string_list = []
  for letter in string:
      string_list.append(letter)
  </code></pre>
  <p>Then, I have a list called encrypt_list which the letters which I want to add in order to encrypt my string.<br />
  So, I use the following code to add a random letter from the encrypt_list after each letter/component in the string_list and then join the list and print as a string.</p>
  <pre class="lang-py prettyprint-override"><code>for i in range(0, len(string) - 1):
      string_list.insert(for letter in string_list: string_list.index(letter) + 1, encrypt_list[random.randint(0, len(encrypt_list) - 1)])
  
  print(&quot;The encrypted string is: &quot;)
  print(''.join(string_list))
  </code></pre>
  <p>I expected the output to be: <strong>1</strong>A<strong>6</strong>b<strong>2</strong>n<strong>7</strong>8<strong>1</strong> (I bolded the letter to show my actual string in it) But I am getting an error, that I cannot use the for loop in the insert function, and I cannot find another way of doing that, please help. Hope I make my problem clear</p>