def pretty_str_time(dt):
    """Get a pretty string for the given datetime object.
    
    Parameters
    ----------
    dt : :obj:`datetime`
        A datetime object to format.
    
    Returns
    -------
    :obj:`str`
        The `datetime` formatted as {year}_{month}_{day}_{hour}_{minute}.
    """
    return '{0}_{1}_{2}_{3}:{4}'.format(dt.year, dt.month, dt.day, dt.hour,
        dt.minute)
