string 'Select a valid choice. That choice is not one of the available choices.' for 'invalid_choice'. define the method __init__ with 13 arguments: self, queryset, empty_label set to a string "---------", cache_choices set to None,
def __init__ ( self , queryset , empty_label = "---------" , cache_choices = None , required = True , widget = None , label = None , initial = None , help_text = '' , to_field_name = None , limit_choices_to = None , * args , ** kwargs ) :