"Create a simple, enchanting black-and-white illustration for a coloring book aimed at children ages 3-5, showing a group of friendly unicorns enjoying a day at the park. Use bold, thick lines for easy coloring. Imagine a scene with the unicorns on a sunny, grassy area, with a few basic playground structures like a slide and a swing set, all drawn in a straightforward style. Add a couple of fluffy clouds and a sun with a smiling face in the sky. The unicorns could be seen frolicking, with one maybe going down a slide and another gently swinging. Ensure the playground and the unicorns are depicted with minimal detail but enough character to spark joy in young colorists. This scene should invite kids to immerse themselves in a magical day at the park, filling it with their favorite colors