raiseRuntimeError("Cluster summary CSV file {} doesn't exist. Should have been created by mu-cluster.".format(clusters_summary_csv_file))
ifnotos.path.isfile(clusters_matches_csv_file):
raiseRuntimeError("CSV file {} with matches per clusters doesn't exist. Should have been created by mu-cluster.".format(clusters_matches_csv_file))
ifnotos.path.isfile(cx_course_students_csv_file):
raiseRuntimeError("Code Expert course data CSV file {} doesn't exist. Download it from Code Expert as follows: My Courses -> Students -> Export to CSV.".format(cx_course_students_csv_file))