SyntaxError：标识符中的无效字符在重写后仍然无效

Question

我已经在我现有代码中复制了一个代码片段，因此得到错误：

    File "qrcode.py", line 51
    return warped
                 ^
    SyntaxError: invalid character in identifier

我做了一些研究，他们都谈到了隐藏符号，我应该自己重写代码。现在重新输入我的代码之后我还有同样的问题。

my codesnippet：

    def four_point_transform(image, pts):
        # compute the width of the new image, which will be the
        # maximum distance between bottom-right and bottom-left
        # x-coordiates or the top-right and top-left x-coordinates
        widthA = np.sqrt(
            ((pts[2][0] - pts[3][0]) ** 2) + ((pts[2][1] - pts[3][1]) ** 2))
        widthB = np.sqrt(
            ((pts[1][0] - pts[0][0]) ** 2) + ((pts[1][1] - pts[0][1]) ** 2))
        maxWidth = max(int(widthA), int(widthB))

        # compute the height of the new image, which will be the
        # maximum distance between the top-right and bottom-right
        # y-coordinates or the top-left and bottom-left y-coordinates
        heightA = np.sqrt(
            ((pts[1][0] - pts[2][0]) ** 2) + ((pts[1][1] - pts[2][1]) ** 2))
        heightB = np.sqrt(
            ((pts[0][0] - pts[3][0]) ** 2) + ((pts[0][1] - pts[3][1]) ** 2))
        maxHeight = max(int(heightA), int(heightB))

        # now that we have the dimensions of the new image, construct
        # the set of destination points to obtain a "birds eye view",
        # (i.e. top-down view) of the image, again specifying points
        # in the top-left, top-right, bottom-right, and bottom-left
        # order
        dst = np.array([
            [0, 0],
            [maxWidth - 1, 0],
            [maxWidth - 1, maxHeight - 1],
            [0, maxHeight - 1]], dtype="float32")

        # compute the perspective transform matrix and then apply it
        M = cv2.getPerspectiveTransform(pts, dst)
        warped = cv2.warpPerspective(image, M, (maxWidth, maxHeight))

        # return the warped image
        return warped