from typing import List


def split_str(data_str: str) -> List[str]:
    """
    Split a string into a list of strings. The string will be split at ',' or '\n' with '\n' taking precedence.
    :param data_str: A string to be split.
    :return: List[str]
    """
    if '\n' in data_str:
        return list(str(data_str).splitlines())
    elif ',' in data_str:
        return list(str(data_str).split(','))
    else:
        i = list()
        i.append(data_str)
        return i