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def iter_binary_search(ordered_list, lower, upper, item):
    """
    Iterative version of binary search
    Test whether item is in ordered_list[lower:upper]
    """

    while lower + 1 < upper:
        mid = (lower + upper) / 2        
        if item < ordered_list[mid]:
            upper = mid
        else:
            lower = mid            
    return item == ordered_list[lower]


def rec1_binary_search(ordered_list, item):
    """
    Recursively check whether item lies in non-empty ordered_list
    """

    if len(ordered_list) == 1:
        return item == ordered_list[0]    
    mid = len(ordered_list) / 2
    if item < ordered_list[mid]:
        return rec1_binary_search(ordered_list[: mid], item)
    else:
        return rec1_binary_search(ordered_list[mid :], item)