def _get_cve_id(full_cve):
    """Return the CVE id from the full CVE JSON dictionary.

    Args:
        full_cve (dict): Full CVE data as a JSON dictionary from API call.

    Returns (str): CVE id (e.g. CVE-2021-26068).
    """
    try:
        return full_cve['id']
    except KeyError:
        return None