<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def list_content_types(repo):
 """ Return a list of content types in a repository. :param Repo repo: The git repository. :returns: list """

    schema_files = glob.glob(
        os.path.join(repo.working_dir, '_schemas', '*.avsc'))
    return [os.path.splitext(os.path.basename(schema_file))[0]
            for schema_file in schema_files]