def df_mask_by_str_or_list(df, column, keys):
    """Find str match and make mask of dataframe.
    If multiple keys are fed, mask will be AND-calculated among keys.
    """
    mask = None
    if type(keys) == str: keys = [keys]
    for key in keys:
        this_mask = df[column].str.find(key) >= 0
        mask = this_mask if mask is None else (mask & this_mask)
    return mask