title: Valid character validation
body: <p>I have tried fixing this code i dont understand why it inst working it is meant to validate that a number has 4 charecters only numbers and no repeats.</p>
  <pre><code>    ValidChr =(&quot;0123456789&quot;,)
      for i in range(num):
          if num.count(i)!= 1:
              return &quot;False&quot;
          if i != ValidChr:
              return &quot;False&quot;
      if length(num) != 4:
          return &quot;False&quot;
      return &quot;True&quot;
  print (Validate(1435))
  </code></pre>