def date_parser(dates):

    """Return list strings in truncated DateTime format ('yyyy-mm-dd').
    
    Args: 
        dates (list): A list containing string values,
            each value in the (DateTime) format 'yyyy-mm-dd hh:mm:ss'.
    
    Return:

    Example:
        Input: date_parser(['2019-11-29 12:50:54', '2019-11-29 12:46:53', '2019-11-29 12:46:10'])
        Output: ['2019-11-29', '2019-11-29', '2019-11-29']
    """
    out = [item[:10] for item in dates]
    return out