def rel_line_to(self, dx, dy):
        """ Relative-coordinate version of :meth:`line_to`.
        Adds a line to the path from the current point
        to a point that is offset from the current point
        by ``(dx, dy)`` in user space.
        After this call the current point will be offset by ``(dx, dy)``.

        Given a current point of ``(x, y)``,
        ``context.rel_line_to(dx, dy)`` is logically equivalent to
        ``context.line_to(x + dx, y + dy)``.

        :param dx: The X offset to the end of the new line.
        :param dy: The Y offset to the end of the new line.
        :type float: dx
        :type float: dy
        :raises:
            :exc:`CairoError` if there is no current point.
            Doing so will cause leave the context in an error state.

        """
        cairo.cairo_rel_line_to(self._pointer, dx, dy)
        self._check_status()