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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 get_tag_hash(self, tag_name):
 """Fetch the commit hash that was tagged with ``tag_name``. Args: tag_name (str):
 the name of the tag Returns: str: the commit hash linked by the tag """

        tag_object = get_single_item_from_sequence(
            sequence=self._github_repository.tags(),
            condition=lambda tag: tag.name == tag_name,
            no_item_error_message='No tag "{}" exist'.format(tag_name),
            too_many_item_error_message='Too many tags "{}" found'.format(tag_name),
        )

        return tag_object.commit.sha