def save_obj(self, path, update_normals=True):
        """Save data with OBJ format
        :param stl path:
        :param bool update_normals:
        """
        if update_normals:
            self.update_normals()

        # Create triangle_list
        vectors_key_list = []
        vectors_list = []
        normals_key_list = []
        normals_list = []
        triangle_list = []
        for i, vector in enumerate(self.vectors):
            one_triangle = []
            for j in range(3):
                v_key = ",".join(map(str, self.vectors[i][j][:3]))
                if v_key in vectors_key_list:
                    v_index = vectors_key_list.index(v_key)
                else:
                    v_index = len(vectors_key_list)
                    vectors_key_list.append(v_key)
                    vectors_list.append(self.vectors[i][j][:3])
                one_triangle.append(v_index + 1)

            n_key = ",".join(map(str, self.normals[i][:3]))
            if n_key in normals_key_list:
                n_index = normals_key_list.index(n_key)
            else:
                n_index = len(normals_key_list)
                normals_key_list.append(n_key)
                normals_list.append(self.normals[i][:3])

            # print(normals_list)
            triangle_list.append((one_triangle, n_index + 1))

        with open(path, "wb") as fh:
            print("# {} {}".format(__title__, __version__), file=fh)
            print("# {}".format(datetime.datetime.now()), file=fh)
            print("# {}".format(__url__), file=fh)
            print("", file=fh)
            for v in vectors_list:
                print("v {} {} {}".format(v[0], v[1], v[2]), file=fh)
            for vn in normals_list:
                print("vn {} {} {}".format(vn[0], vn[1], vn[2]), file=fh)
            for t in triangle_list:
                faces = t[0]
                normal = t[1]

                print("f {}//{} {}//{} {}//{}".format(
                    faces[0], normal,
                    faces[1], normal,
                    faces[2], normal,
                ), file=fh)