CadQuery: Chamfer in sketch minimal example

This code chamfers the top side of a sketch rectangle, which is then extruded

import cadquery as cq

obj = (cq.Workplane("YZ")
    .sketch()
    .rect(1,4)
    # Select vertices to chamfer
    .vertices(">Y") # Top of local Y coordinate system (which is Z axis)
    .chamfer(0.2)
    .finalize()
    .extrude(0.1)
)
obj