code: def to_string(self, obj):
          
          try:
              converted = [str(element) for element in obj]
              string = ','.join(converted)
          except TypeError:
              # for now this is ok for booleans
              string = str(obj)
          return string
docs: Picks up an object and transforms it
          into a string, by coercing each element
          in an iterable to a string and then joining
          them, or by trying to coerce the object directly