parameter: size=1000
[10]
output:  "temp/result.txt"
# added comment
sh:
    dd if=/dev/urandom of=${output} count=${size}

[20]
output:  'temp/size.txt'
with open(output[0], 'w') as sz:
    sz.write("Modified ${input}: ${os.path.getsize(input[0])}\n")