title: Find common values in dictionary that has keys with multiple values
body: <p>I am new to python and I have a problem. I am trying to find keys with a value; however, the keys have multiple values.</p>
  
  <pre><code>d = {
      'a': ['john', 'doe', 'jane'], 
      'b': ['james', 'danny', 'john'], 
      'C':['john', 'scott', 'jane'],
  }
  </code></pre>
  
  <p>I want to find the value <code>john</code> in d and get the keys a, b and c or find <code>jane</code> and get keys a and c.</p>