code: def _set_return(self):
          
          # TODO: manage return retrieved from element code (external)
          # TODO: manage different in/out styles
          if type(self.docs['in']['return']) is list and self.dst.style['out'] not in ['groups', 'numpydoc', 'google']:
              # TODO: manage return names
              # manage not setting return if not mandatory for numpy
              lst = self.docs['in']['return']
              if lst:
                  if lst[0][0] is not None:
                      self.docs['out']['return'] = "%s-> %s" % (lst[0][0], lst[0][1])
                  else:
                      self.docs['out']['return'] = lst[0][1]
                  self.docs['out']['rtype'] = lst[0][2]
          else:
              self.docs['out']['return'] = self.docs['in']['return']
              self.docs['out']['rtype'] = self.docs['in']['rtype']
docs: Sets the return parameter with description and rtype if any