code: def get_size(
              self,
              bucket: str,
              key: str
      ) -> int:
          
          try:
              response = self.get_all_metadata(bucket, key)
              size = response['ContentLength']
              return size
          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 the filesize
          :param bucket: the bucket the object resides in.
          :param key: the key of the object for which size is being retrieved.
          :return: integer equal to filesize in bytes