def filter_blacklist(insertions, genes, field='gene_name'):
    """Filters insertions for blacklisted genes.

    Parameters
    ----------
    insertions : List[Insertion]
        Insertions to filter.
    genes : set[str]
        Symbols of the blacklisted genes.

    Yields
    ------
    Insertion
        Next filtered insertion.

    """
    for ins in insertions:
        if ins.metadata[field] not in genes:
            yield ins
