Resolve "Implement basic functionality"

Closes #1 (closed) Closes #2 (closed) Closes #3 (closed) Closes #4 (closed) Closes #5 (closed) Closes #6 (closed)

example/src/components/NumberCounter.vue

+<template>
+  <div>
+    <p>External counter:</p>
+    <div class="row">
+      <button @click="$emit('input', value - 1)">-</button>
+      {{ value }}
+      <button @click="$emit('input', value + 1)">+</button>
+    </div>
+
+    <p>Internal counter:</p>
+    <div class="row">
+      <button @click="count--">-</button>
+      {{ count }}
+      <button @click="count++">+</button>
+    </div>
+  </div>
+</template>
+
+<script>
+export default {
+  name: "NumberCounter",
+  props: {
+    value: {
+      type: Number,
+      required: true,
+    },
+  },
+  emits: ["input"],
+  data() {
+    return {
+      count: 0,
+    };
+  },
+};
+</script>
+
+<style scoped>
+div {
+  background: #2c3e50;
+  color: white;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  text-align: center;
+  padding: 0.2em;
+  gap: 3px;
+}
+div.row {
+  flex-direction: row;
+  gap: 1em;
+}
+</style>