code: def fromts(ts, tzin=None, tzout=None):
      
      if ts is None:
          return None
      when = datetime.utcfromtimestamp(ts).replace(tzinfo=tzin or utc)
      return totz(when, tzout)
docs: Return the datetime representation of the provided Unix timestamp. By defaults the timestamp is
      interpreted as UTC. If tzin is set it will be interpreted as this timestamp instead. By default
      the output datetime will have UTC time. If tzout is set it will be converted in this timezone
      instead.