human
Complete the below
def create_many_related_manager(superclass, rel):

    ''''Creates a manager that subclasses \'superclass\' (which is a Manager)
    and adds behavior for many-to-many related objects.'
    '''
 ... What is a the Python program you requested?
assistant
#Here is the Python program you requested.
    class ManyRelatedManager(superclass, ):
        def __init__(self, model=None, query_field_name=None, instance=None, symmetrical=None, source_field_name=None, target_field_name=None, reverse=False, through=None, prefetch_cache_name=None):
            super(ManyRelatedManager, self).__init__()
            self.model = model
            self.query_field_name = query_field_name
            self.core_filters = {('%s__pk' % query_field_name): instance._get_pk_val()}
            self.instance = instance
            self.symmetrical = symmetrical
            self.source_field_name = source_field_name
            self.target_field_name = target_field_name
            self.reverse = reverse
            self.through = through
            self.prefetch_cache_name = prefetch_cache_name
            self._fk_val = self._get_fk_val(instance, source_field_name)
            if (self._fk_val is None):
                raise ValueError(('"%r"    needs    to    have    a    value    for    field    "%s"    before    this    many-to-many    relationship    can    be    used.' % (instance, source_field_name)))
            if (instance.pk is None):
                raise ValueError(('%r    instance    needs    to    have    a    primary    key    value    before    a    many-to-many    relationship    can    be    used.' % instance.__class__.__name__))
        def _get_fk_val(self, obj, field_name):
            "\n                                                Returns    the    correct    value    for    this    relationship's    foreign    key.    This\n                                                might    be    something    else    than    pk    value    when    to_field    is    used.\n                                                "
            fk = self.through._meta.get_field(field_name)
            if (fk.rel.field_name and (fk.rel.field_name != fk.rel.to._meta.pk.attname)):
                attname = fk.rel.get_related_field().get_attname()
                return fk.get_prep_lookup('exact', getattr(obj, attname))
    ...