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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 size(self):
        '''Return the area of the patch.
        
        The area can be computed using the standard polygon area formula + signed segment areas of each arc.
        '''
        polygon_area = 0
        for a in self.arcs:
            polygon_area += box_product(a.start_point(), a.end_point())
        polygon_area /= 2.0
        return polygon_area + sum([a.sign * a.segment_area() for a in self.arcs])