Adjust date and time fields to reflect user input if possible.

        Helper function for the `_arrange_fields` of both Record and
        MultiRecord objects.

def _adjust_datetime(self, sampfrom):
        """
        Adjust date and time fields to reflect user input if possible.

        Helper function for the `_arrange_fields` of both Record and
        MultiRecord objects.
        """
        if sampfrom:
            dt_seconds = sampfrom / self.fs
            if self.base_date and self.base_time:
                self.base_datetime = datetime.datetime.combine(self.base_date,
                                                               self.base_time)
                self.base_datetime += datetime.timedelta(seconds=dt_seconds)
                self.base_date = self.base_datetime.date()
                self.base_time = self.base_datetime.time()
            # We can calculate the time even if there is no date
            elif self.base_time:
                tmp_datetime = datetime.datetime.combine(
                    datetime.datetime.today().date(), self.base_time)
                self.base_time = (tmp_datetime
                                  + datetime.timedelta(seconds=dt_seconds)).time()