BSD_RIGHT
BSS_TRAPEZOID, BSD_RIGHT);
bt_shift_leaf(tree, leaf, 0, idx, 1, BSD_RIGHT);
bt_shift_core(tree, node, idx, count, 1, shape, BSD_RIGHT);
BSD_RIGHT);
n - fn, BSD_RIGHT);
bt_shift_leaf(tree, leaf, 0, idx, n, BSD_RIGHT);