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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 unique_slugify(instance, value, slug_field_name='slug', queryset=None, slug_separator='-'):
 """ Calculates and stores a unique slug of ``value`` for an instance. ``slug_field_name`` should be a string matching the name of the field to store the slug in (and the field to check against for uniqueness). ``queryset`` usually doesn't need to be explicitly provided - it'll default to using the ``.all()`` queryset from the model's default manager. """

    slug_field = instance._meta.get_field(slug_field_name)

    slug = getattr(instance, slug_field.attname)
    slug_len = slug_field.max_length

    # Sort out the initial slug, limiting its length if necessary.
    slug = slugify(value)
    if slug_len:
        slug = slug[:slug_len]
    slug = _slug_strip(slug, slug_separator)
    original_slug = slug

    # Create the queryset if one wasn't explicitly provided and exclude the
    # current instance from the queryset.
    if queryset is None:
        queryset = instance.__class__._default_manager.all()
    if instance.pk:
        queryset = queryset.exclude(pk=instance.pk)

    # Find a unique slug. If one matches, at '-2' to the end and try again
    # (then '-3', etc).
    next = 2
    while not slug or queryset.filter(**{slug_field_name: slug}):
        slug = original_slug
        end = '%s%s' % (slug_separator, next)
        if slug_len and len(slug) + len(end) > slug_len:
            slug = slug[:slug_len-len(end)]
            slug = _slug_strip(slug, slug_separator)
        slug = '%s%s' % (slug, end)
        next += 1

    setattr(instance, slug_field.attname, slug)