def split_variant(variant):
    """
    Splits a multi-variant `HGVS` string into a list of single variants. If
    a single variant string is provided, it is returned as a singular `list`.

    Parameters
    ----------
    variant : str
        A valid single or multi-variant `HGVS` string.

    Returns
    -------
    list[str]
        A list of single `HGVS` strings.
    """
    prefix = variant[0]
    if len(variant.split(";")) > 1:
        return ["{}.{}".format(prefix, e.strip()) for e in variant[3:-1].split(";")]
    return [variant]