code: def get_all_metadata(
              self,
              bucket: str,
              key: str
      ) -> dict:
          
          try:
              return self.s3_client.head_object(
                  Bucket=bucket,
                  Key=key
              )
          except botocore.exceptions.ClientError as ex:
              if str(ex.response['Error']['Code']) == \
                      str(requests.codes.not_found):
                  raise BlobNotFoundError(f"Could not find s3://{bucket}/{key}") from ex
              raise BlobStoreUnknownError(ex)
docs: Retrieves all the metadata for a given object in a given bucket.
          :param bucket: the bucket the object resides in.
          :param key: the key of the object for which metadata is being retrieved.
          :return: the metadata