def apply_rows(applicators, rows):
    """
    Yield rows after applying the applicator functions to them.

    Applicators are simple unary functions that return a value, and that
    value is stored in the yielded row. E.g.
    `row[col] = applicator(row[col])`. These are useful to, e.g., cast
    strings to numeric datatypes, to convert formats stored in a cell,
    extract features for machine learning, and so on.

    Args:
        applicators: a tuple of (cols, applicator) where the applicator
            will be applied to each col in cols
        rows: an iterable of rows for applicators to be called on
    Yields:
        Rows with specified column values replaced with the results of
        the applicators

    .. deprecated:: v0.7.0
    """
    for row in rows:
        for (cols, function) in applicators:
            for col in (cols or []):
                value = row.get(col, '')
                row[col] = function(row, value)
        yield row