def convert(k: str) -> str:
    """Convert key of dictionary to valid BQ key.

    :param k: Key
    :return: The converted key
    """
    if len(k.split(":")) > 1:
        k = k.split(":")[1]
    if k.startswith("@") or k.startswith("#"):
        k = k[1:]
    k = k.replace("-", "_")
    return k