old_contents: # encoding: utf-8
  from django import forms
  from .models import Animal
  
  
  class AnimalForm(forms.ModelForm):
      class Meta:
          model = Animal
          exclude = ['codigo',]
  
  
new_contents: # encoding: utf-8
  from django import forms
  from .models import Animal
  from .models import Vacina
  
  
  class AnimalForm(forms.ModelForm):
      class Meta:
          model = Animal
          exclude = ['codigo',]
  
  
  class VacinaForm(forms.ModelForm):
      class Meta:
          model = Vacina
  
  
subject: Update forms.py