title: Hash unique by column and merge other column
body: <p>I have below hash. How to get unique and merged hash.</p>
  
  <pre><code>[
   {
    "email"=&gt;"user_name@aaa.com",
    "expression"=&gt;"aaa",
    "name"=&gt;"bbb",
    "roles"=&gt;[:admin]
    },
  
    {
     "email"=&gt;"user_name@aaa.com",
     "expression"=&gt;"aaa",
     "name"=&gt;"bbb",
     "roles"=&gt;[:manager]
    }
  ]
  </code></pre>
  
  <p>I want below result hash that unique by email and merged by roles.</p>
  
  <pre><code>[
    {
      "email"=&gt;"user_name@aaa.com",
      "expression"=&gt;"aaa",
      "name"=&gt;"bbb",
      "roles"=&gt;[:admin, :manager]
    }
  ]
  </code></pre>
  
  <p>Help me.</p>