def do_OP_SUBSTR(stack):
    pos = nonnegative_int_from_script_bytes(stack.pop())
    length = nonnegative_int_from_script_bytes(stack.pop())
    stack.append(stack.pop()[length:length+pos])
Removes the tag from the object f present.
dataset/ETHPy150Open richardkiss/pycoin/pycoin/tx/script/microcode.py/do_OP_SUBSTR--crossover with--dataset/ETHPy150Open njr0/fish/fish/fishlib.py/Fluidinfo.untag_object