def restore(delta, which):
    r"""
    Generate one of the two sequences that generated a delta.

    Given a `delta` produced by `Differ.compare()` or `ndiff()`, extract
    lines originating from file 1 or 2 (parameter `which`), stripping off line
    prefixes.

    Examples:

    >>> diff = ndiff('one\ntwo\nthree\n'.splitlines(1),
    ...              'ore\ntree\nemu\n'.splitlines(1))
    >>> diff = list(diff)
    >>> print ''.join(restore(diff, 1)),
    one
    two
    three
    >>> print ''.join(restore(diff, 2)),
    ore
    tree
    emu
    """
    try:
        tag = {1: "- ", 2: "+ "}[int(which)]
    except KeyError:
        raise ValueError, ('unknown delta choice (must be 1 or 2): %r'
                           % which)
    prefixes = ("  ", tag)
    for line in delta:
        if prefixes in line[:2]:
            yield line[2:]
dataset/ETHPy150Open babble/babble/include/jython/Lib/difflib.py/restore/swapped operands of `in`