<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def CopyToDateTimeStringISO8601(self):
 """Copies the date time value to an ISO 8601 date and time string. Returns: str: date and time value formatted as an ISO 8601 date and time string or None if the timestamp cannot be copied to a date and time string. """

    date_time_string = self.CopyToDateTimeString()
    if date_time_string:
      date_time_string = date_time_string.replace(' ', 'T')
      date_time_string = '{0:s}Z'.format(date_time_string)
    return date_time_string