def __init__(self, columns):
        "Initializes Columns instance with names and data types."
        self.__column_index = 1
        self.__column_names = UniqueDict()
        for name, data_type in columns:
            self.add(name, data_type)
Initializes Columns instance with names and data types.
recipes/Python/577825_Rudimentary_Database_Engine/recipe-577825.py