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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 _add_block_number_to_hash_lookup(db: BaseDB, header: BlockHeader) -> None: """ Sets a record in the database to allow looking up this header by its block number. """

        block_number_to_hash_key = SchemaV1.make_block_number_to_hash_lookup_key(
            header.block_number
        )
        db.set(
            block_number_to_hash_key,
            rlp.encode(header.hash, sedes=rlp.sedes.binary),
        )