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<!-- Hidden.svelte -->
<script>
let shown = false;
export function show() {
shown = true;
}
</script>
{#if shown}
<slot/>
{/if}
<!-- Parent.svelte -->
<script>
import Hidden from './Hidden.svelte';
let child;
</script>
<Hidden bind:this={child}>
Content
</Hidden>
<button on:click={() => child.show()}>Show</button>