title: How to assign a NULL value to a pointer in python?
body: <p>I am C programmer. I am new to python. In C , when we define the structure of a binary tree node we assign NULL to it's right and left child as :  </p>
  
  <pre><code>struct node 
  {
      int val;  
      struct node *right ;  
      struct node *left ;  
  };   
  </code></pre>
  
  <p>And when initializing a node , we write as :  </p>
  
  <pre><code>val = some_value  
  right = NULL;  
  left = NULL;  
  </code></pre>
  
  <p>Now my question is: how can we assign a NULL value to right and left pointers of the node in Python? </p>
  
  <p>And how can we test against the Python version of NULL ? In C it would be:</p>
  
  <pre><code>if( ptr-&gt;right == NULL )
  </code></pre>
  
  <p>Thank you!</p>