def is_insertion(row):
    """Encodes if the indel is an insertion or deletion.
    
    Args:
        row (pandas.Series): reference seq (str) at index 'ref' 
    Returns:
        is_insertion (int): 0 if insertion, 1 if deletion
    """
    is_insertion = 0

    if row["ref"] == "-":
        is_insertion = 1

    return is_insertion