import re


def get_cloze_nums(content):
    """
    Search content for cloze references and return as a set.

    For example, for the content

        ((c1::I)) ((c2::am)) hungry.

    This would return {1, 2}.
    """
    match = re.findall(r"\(\(c(\d+)::.+?\)\)", content)
    if match:
        cloze_nums = {int(x) for x in match}
    else:
        cloze_nums = set()

    return cloze_nums