<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def trim_struct_time(st, strip_time=False):
 """ Return a `struct_time` based on the one provided but with the extra fields `tm_wday`, `tm_yday`, and `tm_isdst` reset to default values. If `strip_time` is set to true the time value are also set to zero: `tm_hour`, `tm_min`, and `tm_sec`. """

    if strip_time:
        return struct_time(list(st[:3]) + TIME_EMPTY_TIME + TIME_EMPTY_EXTRAS)
    else:
        return struct_time(list(st[:6]) + TIME_EMPTY_EXTRAS)