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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 ReadHashBlobReferences(self, hashes, cursor):
 """Reads blob references of a given set of hashes."""

    query = ("SELECT hash_id, blob_references FROM hash_blob_references WHERE "
             "hash_id IN {}").format(mysql_utils.Placeholders(len(hashes)))
    cursor.execute(query, [hash_id.AsBytes() for hash_id in hashes])
    results = {hash_id: None for hash_id in hashes}
    for hash_id, blob_references in cursor.fetchall():
      sha_hash_id = rdf_objects.SHA256HashID.FromBytes(hash_id)
      refs = rdf_objects.BlobReferences.FromSerializedString(blob_references)
      results[sha_hash_id] = list(refs.items)
    return results