import csv


def readCSV(_filename, _columnName):
    """
    functions to read csv file
    :param _filename: a given file with the extension csv
    :param _columnName: string name of the column to read
    :return: a list
    """
    _list = []
    with open(_filename, 'r') as csvFile:
        r = csv.DictReader(csvFile)
        for row in r:
            _list.append(row[_columnName])
    return _list