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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 CheckBlobsExist(self, blob_ids):
 """Check if blobs for the given digests already exist."""

    res = {blob_id: False for blob_id in blob_ids}

    urns = {self._BlobUrn(blob_id): blob_id for blob_id in blob_ids}

    existing = aff4.FACTORY.MultiOpen(
        urns, aff4_type=aff4.AFF4MemoryStreamBase, mode="r")

    for blob in existing:
      res[urns[blob.urn]] = True

    return res