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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 check_save(sender, **kwargs):
 """ Checks item type uniqueness, field applicability and multiplicity. """

    tag = kwargs['instance']
    obj = Tag.get_object(tag)
    previous_tags = Tag.get_tags(obj)
    
    err_uniq = check_item_type_uniqueness(tag, previous_tags)
    err_appl = check_field_applicability(tag)
    err_mult = check_field_multiplicity(tag, previous_tags)
    err_msg = generate_error_message(tag, err_uniq, err_appl, err_mult)
    if err_uniq or err_appl or err_mult:
        raise TypeError(err_msg)