run test/grayscale.py 
bt
catch throw
run test/grayscale.py 
bt
run test/grayscale.py 
bt
catch throw
run test/grayscale.py 
bt
y
catch throw
run  test/grayscale.py 
bt
catch throw
run test/grayscale.py 
bt
f 4
info args
print (expected.at(0))
print (expected.at(0)[0])
run  grayscale.py
run test/grayscale.py
catch throw
run test/grayscale.py
run test/grayscale.py 
catch throw
run test/grayscale.py 
bt
y
