import cadquery as cq
w0=cq.Workplane('YZ',origin=(-50,0,0))
r=w0.sketch().segment((-15,-16),(-6,-16)).segment((-6,-31)).segment((6,-31)).segment((6,-16)).segment((15,-16)).segment((15,17)).segment((6,17)).segment((6,31)).segment((-6,31)).segment((-6,17)).segment((-15,17)).close().assemble().finalize().extrude(100)