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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 approx_equals(self, other, atol):
 """Return ``True`` in case of approximate equality. Returns ------- approx_eq : bool ``True`` if ``other`` is a `RectPartition` instance with ``self.set == other.set`` up to ``atol`` and ``self.grid == other.other`` up to ``atol``, ``False`` otherwise. """

        if other is self:
            return True
        elif not isinstance(other, RectPartition):
            return False
        else:
            return (self.set.approx_equals(other.set, atol=atol) and
                    self.grid.approx_equals(other.grid, atol=atol))