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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def construct_form(self, request):
 """ Constructs form from POST method using self.form_class. """

        if not hasattr(self, 'form_class'):
            return None

        if request.method == 'POST':
            form = self.form_class(self.model, request.POST, request.FILES)
        else:
            form = self.form_class(self.model)
        return form