"Create a delightful black-and-white illustration for a children’s coloring book, suitable for ages 3-5, depicting a group of unicorns at the park. The scene should feature bold, thick lines to make coloring easy for young children. Picture the unicorns playing on a grassy field surrounded by trees, with a simple playground in the background. Include elements like swings, slides, and seesaws, as well as colorful balloons floating in the sky. The unicorns should be shown engaging in playful activities, such as chasing butterflies, playing tag, or simply enjoying each other’s company. Keep the details simple and inviting, allowing plenty of space for children to add their creative touches with colors. This scene aims to capture the joy and magic of a day out at the park with friends.