code: def get_content_type(
              self,
              bucket: str,
              key: str
      ) -> str:
          
          response = self.get_all_metadata(bucket, key)
          # hilariously, the ETag is quoted.  Unclear why.
          return response['ContentType']
docs: Retrieves the content-type 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 content-type is being retrieved.
          :return: the content-type