string 'Enter a list of values.' for 'list', return value of the function _ called with an argument, string 'Select a valid choice. %(value)s is not one of the available choices.' for 'invalid_choice', and return value of the function _ called with an argument string '"%(pk)s" is not a valid value for a primary key.' for 'invalid_pk_value'. define the method __init__ with 10 arguments: self, queryset, cache_choices set to None, required set to boolean True,
def __init__ ( self , queryset , cache_choices = None , required = True , widget = None , label = None , initial = None , help_text = '' , * args , ** kwargs ) :