def unpack_quantity(row, concept, value):
    """Unpack row like {"variable": [{"concept":<concept>, <value>:_i_want_this_}]}

    Args:
        row (dict): Row of Worldbank API data.
        concept (str): The name of the dataset containing the variable.
        value (str): The name of the variable to unpack.
    Returns:
        A value.
    """
    for quantity in row['variable']:
        if quantity['concept'] == concept:
            return quantity[value]
    raise NameError(f"No item found in {row['variable']} with "
                    f"concept = {concept}")