from datetime import datetime

def process_time(data, time_columns, format='%Y-%m-%d %H:%M:%S'):
    # format for uber: '%m/%d/%y %H:%M'
    # format for cabs: '%Y-%m-%d %H:%M:%S'
    # IT PROCESSES IT IN PLACE!

    # if data_name is None ignore format
    if data_name is None:
        for time_col in time_columns:
            data[time_col] = pd.to_datetime(data[time_col], format=format)
            data[time_col] = data[time_col].apply(lambda x: datetime(month=x.month, year=x.year, day=1))