title: Django ManyToMany relation contains value
body: <p>I'm trying to search through a ManyToMany relationship, but I'm doing something wrong and I'm not sure about what it is</p>
  
  <pre><code>t = Teacher.objects.get(username=u.username)
  var = list(Allowed.objects.filter(allowed=t))
  </code></pre>
  
  <p>This is the class I'm using:</p>
  
  <pre><code>class Allowed(models.Model):
    owner = models.ForeignKey(Teacher, related_name='allowed_teacher')
    reason = models.CharField(max_length=200, blank=True, null=True)
    allowed = models.ManyToManyField(Teacher, related_name='who_is_allowed', blank=True, null=True)
  </code></pre>
  
  <p>How can I do it?</p>
  
  <p><strong>EDIT:</strong>
  <code>Teacher</code> doesn't have any reference to Allowed</p>