title: Python dictionary check if the values match with other key values
body: <p>I have created a python dictionary with a structure like :-</p>
  
  <pre><code>mydict = {'2018-08' : [32124,4234,23,2323,32423,342342],
            '2018-07' : [13123,23424,2,3,4343,4232,2342],
            '2018-06' : [1231,12,12313,12331,3123131313,434546,232]}
  </code></pre>
  
  <p>I want to check if any value in the values of key <code>'2018-08'</code> match with any values of other keys. is there a short way to write this?</p>