title: ImportError: cannot import name and Cannot import class
body: <p>I got a full code from github and everything was OK, server worked without any problems. But then I tried to do some changes, like adding a new class in the <code>model.py</code> and trying to import it to the <code>admin.py</code> I got such an error: </p>
  
  <blockquote>
    <p>ImportError: cannot import name TechnicalExamination. </p>
  </blockquote>
  
  <p>Of course, I did migrations before this, using <code>python manage.py makemigrations</code> and <code>python manage.py migrate</code>.</p>
  
  <p>Here is my class in models.py:</p>
  
  <pre><code>class HealthExamination(models.Model):
  class Meta:
      verbose_name_plural = 'Health Examinations'
  
  doctor = models.CharField(max_length=70)
  person = models.ForeignKey(Person, on_delete=models.CASCADE)
  start_date = models.DateField()
  end_date = models.DateField()
  
  class TechnicalExamination(models.Model):
    class Meta:
      verbose_name_plural = 'Technical Examinations'
  
    technician = models.CharField(max_length=70)
    person = models.ForeignKey(Person, on_delete=models.CASCADE)
    start_date = models.DateField()
    end_date = models.DateField()
  
  def get_fields(self):
      pairs = []
      for field in self._meta.fields:
          name = field.name
          try:
              pairs.append((name, getattr(self, "get_%s_display" % name)()))
          except AttributeError:
              pairs.append((name, getattr(self, name)))
      return pairs
  
  def __str__(self):
    return str(self.person)
  </code></pre>
  
  <p>Here is my admin.py:</p>
  
  <pre><code>from __future__ import unicode_literals
  
  from django.contrib import admin
  
  from .models import Person, Car, InsuranceCompany, Policy,   HealthExamination, TechnicalExamination
  
  admin.site.register(Person)
  admin.site.register(Car)
  admin.site.register(InsuranceCompany)
  admin.site.register(Policy)
  admin.site.register(HealthExamination)
  admin.site.register(TechnicalExamination)
  </code></pre>
  
  <p>And here is my root:</p>
  
  <p><a href="https://i.stack.imgur.com/fVLWu.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fVLWu.jpg" alt="enter image description here"></a></p>