def matcher(source):
    """
    Matches user input with datasets, the lists can be extended
    """
    matcher_map = {"power_plant": ["coal", "coals", "natural gas", "gas", "bioenergy",
                                   "biomass", "hard coal", "lignite", "Fossil fuels",
                                   "fossil", "basic"],
                   "cement": ["cement"],
                   "iron": ["iron", "steel", "iron and steel"]}

    key = dict(filter(lambda x: source in x[1], matcher_map.items())).keys()

    return list(key)[0]