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This stretch is very useful at loosening up your groin and inner thigh muscles, which are crucial to executing a Chinese split.  Sit on the floor with your back straight.  Bend your knees and bring the soles of your feet together in front of you.  Slowly pull your heels in towards your groin. Try to get your heels as close to you as you comfortably can, and keep your hands gripping your ankles.  Gently flex your knees down until they are touching the floor, or as close to the floor as you can comfortably get them. You can use your elbows to push your knees downward.  While exhaling, bend forward at the waist, and try to get your chest as close to the floor as possible. Hold the position for 20 seconds, then release it. This yoga position will help you stretch and loosen the muscles in your groin, calves, and quads, all major muscle groups needed to do a Chinese split.  Begin by lying flat on your back. As you exhale, pull your knees up towards your stomach.  While holding the outsides of each foot in your hands, open your knees just past the width of your abdomen, and pull your knees towards your armpits.  Try to keep your shins perpendicular to the floor. Hold the position for as long as you comfortably can (around 10 to 30 seconds should be sufficient), then release the pose. This yoga pose might be one of the best stretches to prepare your body for doing Chinese splits. Take it slow, though, as this position may be strenuous for first-time practitioners.  Begin by entering a staff pose. Sit on the floor with your back straight and your legs fully extended in front of you, with the insides of your feet touching.  Spread both legs outward. Try to form both legs into 90 degree angles with your hips. Slide your bottom slightly forward while keeping your legs spread to help push your legs as wide as you can comfortably spread them.  While keeping your knee caps pointed upward, stretch your hands forward between your legs as far as you can go without bending at the waist.  Hold the pose for around one minute, or as long as you comfortably can. Then release the pose.
Do a butterfly stretch. Practice the Happy Baby pose. Do a wide-angle seated forward bend.