How to use the labelme.utils.distance function in labelme

def closeEnough(self, p1, p2):
        # d = distance(p1 - p2)
        # m = (p1-p2).manhattanLength()
        # print "d %.2f, m %d, %.2f" % (d, m, d - m)
        # divide by scale to allow more precision when zoomed in
        return labelme.utils.distance(p1 - p2) < (self.epsilon / self.scale)

def nearestVertex(self, point, epsilon):
        min_distance = float('inf')
        min_i = None
        for i, p in enumerate(self.points):
            dist = labelme.utils.distance(p - point)
            if dist <= epsilon and dist < min_distance:
                min_distance = dist
                min_i = i
        return min_i

x3, y3 = points[i]
            x4, y4 = points[(i + 1) % 4]
            denom = (y4 - y3) * (x2 - x1) - (x4 - x3) * (y2 - y1)
            nua = (x4 - x3) * (y1 - y3) - (y4 - y3) * (x1 - x3)
            nub = (x2 - x1) * (y1 - y3) - (y2 - y1) * (x1 - x3)
            if denom == 0:
                # This covers two cases:
                #   nua == nub == 0: Coincident
                #   otherwise: Parallel
                continue
            ua, ub = nua / denom, nub / denom
            if 0 <= ua <= 1 and 0 <= ub <= 1:
                x = x1 + ua * (x2 - x1)
                y = y1 + ua * (y2 - y1)
                m = QtCore.QPoint((x3 + x4) / 2, (y3 + y4) / 2)
                d = labelme.utils.distance(m - QtCore.QPoint(x2, y2))
                yield d, i, (x, y)