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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _push_condition(predicate):
 """As we enter new conditions, this pushes them on the predicate stack."""

    global _depth
    _check_under_condition()
    _depth += 1
    if predicate is not otherwise and len(predicate) > 1:
        raise PyrtlError('all predicates for conditional assignments must wirevectors of len 1')
    _conditions_list_stack[-1].append(predicate)
    _conditions_list_stack.append([])