def do_OP_CAT(stack):
    v1 = stack.pop()
    v2 = stack.pop()
    stack.append(v2 + v1)
Handles the user clicking one of the custom check boxes.
dataset/ETHPy150Open richardkiss/pycoin/pycoin/tx/script/microcode.py/do_OP_CAT--crossover with--dataset/ETHPy150Open enthought/traitsui/traitsui/qt4/check_list_editor.py/CustomEditor.update_object