Assertion: endoscope's channel | /r/HasProperty | necessary
Facets:
Source sentences:
text: The endoscope consist of a fiber optic tube that is usually flexible, but may sometimes be rigid; a tiny camera at the end of the tube; a light source outside the body to transmit light through the tube, thus illuminating the organ or cavity; and a second channel, which the doctor can use in case a biopsy or any other intervention is necessary.