<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def reference_source_point(self):
 """ The location of the source in the reference image, in terms of the current image coordinates. """

        xref = isinstance(self.xref, Quantity) and self.xref.value or self.xref
        yref = isinstance(self.yref, Quantity) and self.yref.value or self.yref

        return xref + self.x_ref_offset, yref + self.y_ref_offset