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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 to_bytes_or_none(value):
 """Converts C char arrays to bytes and C NULL values to None."""

    if value == ffi.NULL:
        return None
    elif isinstance(value, ffi.CData):
        return ffi.string(value)
    else:
        raise ValueError('Value must be char[] or NULL')