Django. Using f () to solve the competition problem

What are the competition issues:
When multiple users operate on a field at the same time, there is no expected return.
F () function:

from django.db.models import F

def vote(request, choice_id):
    selected_choice = question.choice_set.get(pk=request.POST['choice'])
    selected_choice.votes = F('votes') + 1
    selected_choice.save()

 


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