code: def new_reviewer(self, name, anomalous=None):
          
          n = self._reviewer_cls(
              self, name=name, credibility=self.credibility, anomalous=anomalous)
          self.graph.add_node(n)
          self.reviewers.append(n)
          return n
docs: Create a new reviewer.
  
          Args:
            name: name of the new reviewer.
            anomalous: initial anomalous score. (default: None)
  
          Returns:
            A new reviewer instance.