Scale the object.

            >>> obj.transformBy(2.0)
            >>> obj.transformBy((0.5, 2.0), origin=(500, 500))

        **value** must be an iterable containing two
        :ref:`type-int-float` values defining the x and y
        values to scale the object by. **origin** defines the
        point at with the scale should originate. It must be
        a :ref:`type-coordinate` or ``None``. The default is
        ``(0, 0)``.

def scaleBy(self, value, origin=None):
        """
        Scale the object.

            >>> obj.transformBy(2.0)
            >>> obj.transformBy((0.5, 2.0), origin=(500, 500))

        **value** must be an iterable containing two
        :ref:`type-int-float` values defining the x and y
        values to scale the object by. **origin** defines the
        point at with the scale should originate. It must be
        a :ref:`type-coordinate` or ``None``. The default is
        ``(0, 0)``.
        """
        value = normalizers.normalizeTransformationScale(value)
        if origin is None:
            origin = (0, 0)
        origin = normalizers.normalizeCoordinateTuple(origin)
        self._scaleBy(value, origin=origin)