title: Find key by inner map value in Elixir
body: <p>Let's suppose i have:</p>
  
  <p><code>%{apple: %{color: red, id: 1}, pear: %{color: green, id: 2}}</code></p>
  
  <p>What is fastest way to get key (apple, for example) looping by value (ex, color: red)</p>