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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 _realign(seq, precursor, start):
 """ The actual fn that will realign the sequence """

    error = set()
    pattern_addition = [[1, 1, 0], [1, 0, 1], [0, 1, 0], [0, 1, 1], [0, 0, 1], [1, 1, 1]]
    for pos in range(0, len(seq)):
        if seq[pos] != precursor[(start + pos)]:
            error.add(pos)

    subs, add = [], []
    for e in error:
        if e < len(seq) - 3:
            subs.append([e, seq[e], precursor[start + e]])

    pattern, error_add = [], []
    for e in range(len(seq) - 3, len(seq)):
        if e in error:
            pattern.append(1)
            error_add.append(e)
        else:
            pattern.append(0)
    for p in pattern_addition:
        if pattern == p:
            add = seq[error_add[0]:]
            break
    if not add and error_add:
        for e in error_add:
            subs.append([e, seq[e], precursor[start + e]])

    return subs, add