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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 get_install_id(filename):
 """ Return install id from library named in `filename` Returns None if no install id, or if this is not an object file. Parameters filename : str filename of library Returns ------- install_id : str install id of library `filename`, or None if no install id """

    lines = _cmd_out_err(['otool', '-D', filename])
    if not _line0_says_object(lines[0], filename):
        return None
    if len(lines) == 1:
        return None
    if len(lines) != 2:
        raise InstallNameError('Unexpected otool output ' + '\n'.join(lines))
    return lines[1].strip()