old_contents: import pytz
  
  from pyrfc3339.utils import timezone, timedelta_seconds
  
  
  def generate(dt, utc=True, accept_naive=False, microseconds=False):
      '''
      Generate an :RFC:`3339`-formatted timestamp from a
      :class:`datetime.datetime`.
  
      >>> from datetime import datetime
      >>> generate(datetime(2009,01,01,12,59,59,0,pytz.utc))
      '2009-01-01T12:59:59Z'
  
      The timestamp will use UTC unless `utc=False` is specified, in which case
      it will use the timezone from the :class:`datetime.datetime`'s
      :attr:`tzinfo` parameter.
  
      >>> eastern = pytz.timezone('US/Eastern')
      >>> dt = eastern.localize(datetime(2009,01,01,12,59,59))
      >>> generate(dt)
      '2009-01-01T17:59:59Z'
      >>> generate(dt, utc=False)
      '2009-01-01T12:59:59-05:00'
  
      Unless `accept_naive=True` is specified, the `datetime` must not be naive.
  
      >>> generate(datetime(2009,01,01,12,59,59,0))
      Traceback (most recent call last):
      ...
      ValueError: naive datetime and accept_naive is False
  
      >>> generate(datetime(2009,01,01,12,59,59,0), accept_naive=True)
      '2009-01-01T12:59:59Z'
  
      If `accept_naive=True` is specified, the `datetime` is assumed to be UTC.
      Attempting to generate a local timestamp from a naive datetime will result
      in an error.
  
      >>> generate(datetime(2009,01,01,12,59,59,0), accept_naive=True, utc=False)
      Traceback (most recent call last):
      ...
      ValueError: cannot generate a local timestamp from a naive datetime
  
      '''
      if dt.tzinfo == None:
          if accept_naive is True:
              if utc is True:
                  dt = dt.replace(tzinfo=pytz.utc)
              else:
                  raise ValueError("cannot generate a local timestamp from " +
                                   "a naive datetime")
          else:
              raise ValueError("naive datetime and accept_naive is False")
  
      if utc is True:
          dt = dt.astimezone(pytz.utc)
  
      timestamp = dt.strftime('%Y-%m-%dT%H:%M:%S')
      if microseconds is True:
          timestamp += dt.strftime('.%f')
      if dt.tzinfo is pytz.utc:
          timestamp += 'Z'
      else:
          timestamp += timezone(timedelta_seconds(dt.tzinfo.utcoffset(dt)))
  
      return timestamp
  
new_contents: import pytz
  
  from pyrfc3339.utils import timezone, timedelta_seconds
  
  
  def generate(dt, utc=True, accept_naive=False, microseconds=False):
      '''
      Generate an :RFC:`3339`-formatted timestamp from a
      :class:`datetime.datetime`.
  
      >>> from datetime import datetime
      >>> generate(datetime(2009,1,1,12,59,59,0,pytz.utc))
      '2009-01-01T12:59:59Z'
  
      The timestamp will use UTC unless `utc=False` is specified, in which case
      it will use the timezone from the :class:`datetime.datetime`'s
      :attr:`tzinfo` parameter.
  
      >>> eastern = pytz.timezone('US/Eastern')
      >>> dt = eastern.localize(datetime(2009,1,1,12,59,59))
      >>> generate(dt)
      '2009-01-01T17:59:59Z'
      >>> generate(dt, utc=False)
      '2009-01-01T12:59:59-05:00'
  
      Unless `accept_naive=True` is specified, the `datetime` must not be naive.
  
      >>> generate(datetime(2009,1,1,12,59,59,0))
      Traceback (most recent call last):
      ...
      ValueError: naive datetime and accept_naive is False
  
      >>> generate(datetime(2009,1,1,12,59,59,0), accept_naive=True)
      '2009-01-01T12:59:59Z'
  
      If `accept_naive=True` is specified, the `datetime` is assumed to be UTC.
      Attempting to generate a local timestamp from a naive datetime will result
      in an error.
  
      >>> generate(datetime(2009,1,1,12,59,59,0), accept_naive=True, utc=False)
      Traceback (most recent call last):
      ...
      ValueError: cannot generate a local timestamp from a naive datetime
  
      '''
      if dt.tzinfo == None:
          if accept_naive is True:
              if utc is True:
                  dt = dt.replace(tzinfo=pytz.utc)
              else:
                  raise ValueError("cannot generate a local timestamp from " +
                                   "a naive datetime")
          else:
              raise ValueError("naive datetime and accept_naive is False")
  
      if utc is True:
          dt = dt.astimezone(pytz.utc)
  
      timestamp = dt.strftime('%Y-%m-%dT%H:%M:%S')
      if microseconds is True:
          timestamp += dt.strftime('.%f')
      if dt.tzinfo is pytz.utc:
          timestamp += 'Z'
      else:
          timestamp += timezone(timedelta_seconds(dt.tzinfo.utcoffset(dt)))
  
      return timestamp
  
subject: Fix doctests for python3