Xform no output

[hclaus]

I am totally new to radiance, I try to follow Radiance_cookbook, but I am stuck in 2.1.2
cat lights.rad !xform -t 1 1 2.95 -a 3 -t 1 0 0 -a 4 -t 0 1 0 erco.rad
in python I don't have a lights.rad and want to add it (later) to B1.rad
tr=pr.Xform(inp="B1.rad").translate(1,1,2.95)
out_str = tr.args
print(out_str)
tr is empty and doesn't recognize decode().
How do I use Xform correctly?

[taoning]

Do this instead:
tr=pr.Xform(inp="B1.rad").translate(1,1,2.95)()