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当前求和为:???
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diff --git a/vue2-tutorials/single-file/demo2/src/views/demo4/index.vue b/vue2-tutorials/single-file/demo2/src/views/demo4/index.vue
new file mode 100644
index 0000000..da7549e
--- /dev/null
+++ b/vue2-tutorials/single-file/demo2/src/views/demo4/index.vue
@@ -0,0 +1,3 @@
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