AttributeError Объект не имеет атрибута

получение AttributeError at /url/ 'SignUpForm' object has no attribute 'newsletter', when trying to sign up a new user

#views
from somewhere.views import subscribe

def createaccount(request):
    if request.method == 'POST':
        form = SignUpForm(request.POST)
        if form.is_valid():
            user = form.save()

            if form.newsletter == True:
                email = request.POST['email']
                subscribe(email)
            else:
                pass

            login(request, user)
            return redirect('main:home')

#forms
class SignUpForm(UserCreationForm):
    newsletter = forms.BooleanField(label="Subscribe to Newsletter", required=False)

if form.cleaned_data['newsletter'] == True:
    # Rest of code