def METHOD_NAME(self):
    """
    Return the cells of ``self``.
    EXAMPLES::
        sage: from sage.categories.cw_complexes import CWComplexes
        sage: X = CWComplexes().example()
        sage: C = X.cells()
        sage: sorted((d, C[d]) for d in C.keys())
        [(0, (0-cell v,)),
         (1, (0-cell e1, 0-cell e2)),
         (2, (2-cell f,))]
    """
    d = {0: (self.element_class(self, 0, 'v'),)}
    d[1] = tuple([self.element_class(self, 0, 'e'+str(e)) for e in self._edges])
    d[2] = (self.an_element(),)
    return Family(d)