MEDICAL DEVICES, NAMELY, GASTROINTESTINAL LINERS OF ARTIFICIAL MATERIAL, SLEEVES AND ANCHOR IMPLANTS OF ARTIFICIAL MATERIAL FOR GASTROINTESTINAL LINERS, DELIVERY SYSTEMS COMPRISING A GASTROINTESTINAL LINER IMPLANT OF ARTIFICIAL MATERIAL AND AN ENDOSCOPIC DELIVERY CATHETER, RETRIEVAL SYSTEMS COMPRISING AN ENDOSCOPIC GRASPER AND ENDOSCOPIC HOOD FOR REMOVAL OF SLEEVES, GASTROINTESTINAL RESISTORS, GASTROINTESTINAL LINER IMPLANTS OF ARTIFICIAL MATERIAL AND RESISTOR COMBINATIONS