Create a new reviewer.

        Args:
          name: name of the new reviewer.
          anomalous: initial anomalous score. (default: None)

        Returns:
          A new reviewer instance.

def new_reviewer(self, name, anomalous=None):
        """Create a new reviewer.

        Args:
          name: name of the new reviewer.
          anomalous: initial anomalous score. (default: None)

        Returns:
          A new reviewer instance.
        """
        n = self._reviewer_cls(
            self, name=name, credibility=self.credibility, anomalous=anomalous)
        self.graph.add_node(n)
        self.reviewers.append(n)
        return n