title: Define a counter type column in django models using cql engine
body: <p>I have a model with counter type column as below:</p>
  
  <pre><code>from cqlengine import columns
  from cqlengine.models import Model
  
  class CountView(Model):
      entryLink=columns.Text(primary_key=True)
      visited=columns.Counter()
  </code></pre>
  
  <p>But when i want create table from this model as below:</p>
  
  <pre><code>&gt;&gt;&gt; from cqlengine import connection
  &gt;&gt;&gt; from cqlengine.management import create_table
  &gt;&gt;&gt; from MainAPP.models import CountView
  </code></pre>
  
  <p>I receive this error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;console&gt;", line 1, in &lt;module&gt;
    File "H:/Web-Programming/Python/Project/Prexter\MainAPP\models.py", line 66, in &lt;module&gt;
  class CountView(Model):
    File "H:/Web-Programming/Python/Project/Prexter\MainAPP\models.py", line 68, in CountView
  visited=columns.Counter()
    File "H:\Web-Programming\Python\Project\Prexter\Virtual-Environment\Lib\site-packages\cqlengine\columns.py", line 421, in __init__
  raise NotImplementedError
  NotImplementedError
  </code></pre>
  
  <p>What is my wrong? How i must define a <strong>counter type</strong> column in my model? Please guide me...</p>