title: How do I add to the default permissions of a model in Django
body: <p>I have my user</p>
  
  <pre><code>class User(AbstractBaseUser, PermissionsMixin):
      ...
  </code></pre>
  
  <p>I want to add a default permission to this class in addition to the default ones provided by django</p>
  
  <pre><code>add: user.has_perm('foo.add_user')
  change: user.has_perm('foo.change_user')
  delete: user.has_perm('foo.delete_user')
  </code></pre>
  
  <p>how do I go about this</p>
  
  <p>will this overite the default?</p>
  
  <pre><code>class User(AbstractBaseUser, PermissionsMixin):
      # model stuff here
      class Meta:
          permissions = ( 
              ( "extra_user", "Can do extra" ),
          )
  </code></pre>