title: Select most common domain from list of email addresses
body: <p>I have a function that generates a random email address:</p>
  
  <pre><code>def emails
      names = ["alfred", "daniel", "elisa", "ana", "ramzes"]
      surnames = ["oak", "leaf", "grass", "fruit"]
      providers = ["gmail", "yahoo", "outlook", "icloud"]
      address = "#{names.sample}.#{surnames.sample}#{rand(100..5300)}@#{providers.sample}.com"
  end
  </code></pre>
  
  <p>Given a list of randomly generated email address:</p>
  
  <pre><code>email_list = 100.times.map { emails }
  </code></pre>
  
  <p>that looks like this:</p>
  
  <pre><code>daniel.oak3985@icloud.com
  ramzes.grass1166@icloud.com
  daniel.fruit992@yahoo.com
  ...
  </code></pre>
  
  <p>how can I select the most common provider ("gmail", "yahoo", etc.)?    </p>