def METHOD_NAME(engine, diffs):
    with engine.begin() as conn:
        ctx = get_migration_context(conn)
        op = Operations(ctx)
        col_diffs = _filter_diffs(diffs, [DiffTypes.ADD_NULLABLE_COLUMN])
        for diff in col_diffs:
            col = diff.column
            table_name = col.table.name
            # the column has a reference to a table definition that already
            # has the column defined, so remove that and add the column
            col.table = None
            op.add_column(table_name, col)
    return col_diffs