import re


def get_chapter_section(string):
    """ Given a line of text, extract the chapter-section if it exists
    :param string: string from which to extract the chapter-section number
    :return: chapter-section if one exists
    """
    chap_sec = []

    # Check if chapter-section contains a colon
    get_colon = re.search("^\d+:", string)
    if get_colon is not None:
        chap_sec = string.split(':')
    else:
        chap_sec = string.split('-')
    return chap_sec