class Tag(models.Model):
    """
    model for tag
    """
    # name of tag
    name = models.CharField(max_length=30, verbose_name="tag name", unique=True)
    def __str__(self):
        return self.name
class Note(models.Model):
    """
    model for note
    """
    # date of publication note
    publication_date = models.DateField("Publication date", auto_now_add=True)
    # date of last change
    date_last_change = models.DateField("Last changed", auto_now=True)
    # note title
    title = models.CharField(max_length=200, verbose_name="Note title")
    # main text of note
    main_text = models.TextField("Note text")
    # tags
    tags = models.ManyToManyField(Tag, related_name='Tags')
    def __str__(self):
        return self.title