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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 _generate_genesis_block(self):
 """ Returns a blocker wrapper with the basics of the block header in place """

        genesis_header = block_pb2.BlockHeader(
            block_num=0,
            previous_block_id=NULL_BLOCK_IDENTIFIER,
            signer_public_key=self._identity_signer.get_public_key().as_hex())

        return BlockBuilder(genesis_header)