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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 length(ext_id, ext_des, ext_src):
        # type: (bytes, bytes, bytes) -> int
        '''
        Static method to return the length of the Rock Ridge Extensions Reference
        record.

        Parameters:
         ext_id - The extension identifier to use.
         ext_des - The extension descriptor to use.
         ext_src - The extension specification source to use.
        Returns:
         The length of this record in bytes.
        '''
        return 8 + len(ext_id) + len(ext_des) + len(ext_src)