code: def to_string(self, style=None, utcoffset=None):
          
          if not style:
              style = self.style
          if utcoffset is None:
              string = ''
              date = self.datetime
          else:
              sign = '+' if utcoffset >= 0 else '-'
              hours = abs(utcoffset // 60)
              minutes = abs(utcoffset % 60)
              string = f'{sign}{hours:02d}:{minutes:02d}'
              offset = utcoffset-hydpy.pub.options.utcoffset
              date = self.datetime + datetime.timedelta(minutes=offset)
          return date.strftime(self._formatstrings[style]) + string
docs: Return a |str| object representing the actual date in
          accordance with the given style and the eventually given
          UTC offset (in minutes).
  
          Without any input arguments, the actual |Date.style| is used
          to return a date string in your local time zone:
  
          >>> from hydpy import Date
          >>> date = Date('01.11.1997 00:00:00')
          >>> date.to_string()
          '01.11.1997 00:00:00'
  
          Passing a style string affects the returned |str| object, but
          not the |Date.style| property:
  
          >>> date.style
          'din1'
          >>> date.to_string(style='iso2')
          '1997-11-01 00:00:00'
          >>> date.style
          'din1'
  
          When passing the `utcoffset` in minutes, the offset string is
          appended:
  
          >>> date.to_string(style='iso2', utcoffset=60)
          '1997-11-01 00:00:00+01:00'
  
          If the given offset does not correspond to your local offset
          defined by |Options.utcoffset| (which defaults to UTC+01:00),
          the date string is adapted:
  
          >>> date.to_string(style='iso1', utcoffset=0)
          '1997-10-31T23:00:00+00:00'