import cadquery as cq
w0=cq.Workplane('ZX',origin=(0,30,0))
r=w0.sketch().circle(50).reset().face(w0.sketch().segment((-18,17),(-1,17)).segment((-1,36)).segment((-1,37)).segment((-18,37)).segment((-18,36)).arc((-22,27),(-18,17)).assemble(),mode='s').finalize().extrude(-61)