Slots are part of the native Web Component. Because LEGO builds native Web Components, you can use the standard slots as documented.

Example #

index.html

<user-profile>
  <span>This user is in Paris</span>
</user-profile>

bricks/user-profile.html

<template>
  <h1>User profile</h1>
  <p>Important information: <slot></slot></p>
</template>

Outputs:

<h1>User profile</h1>
<p>Important information: <span>This user is in Paris</span></p>

See more advanced examples.