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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 find_line_containing(strings: Sequence[str], contents: str) -> int: """ Finds the index of the line in ``strings`` that contains ``contents``, or ``-1`` if none is found. """

    for i in range(len(strings)):
        if strings[i].find(contents) != -1:
            return i
    return -1