def get_now_datetime_filestamp(longTime=False):
    """
    *A datetime stamp to be appended to the end of filenames: 'YYYYMMDDtHHMMSS'*

    **Key Arguments**

    - ``longTime`` -- make time string longer (more change of filenames being unique)

    **Return**

    - ``now`` -- current time and date in filename format

    **Usage**

    ```python
    from fundamentals.download import get_now_datetime_filestamp
    get_now_datetime_filestamp(longTime=False)
    #Out: '20160316t154635'

    get_now_datetime_filestamp(longTime=True)
    #Out: '20160316t154644133638' 
    ```
    """
    from datetime import datetime, date, time
    now = datetime.now()
    if longTime:
        now = now.strftime('%Y%m%dt%H%M%S%f')
    else:
        now = now.strftime('%Y%m%dt%H%M%S')
    return now
