code: def set(self, key, value, confidence=100):
          
          if value is None:
              return
          if key in self.info:
              old_confidence, old_value = self.info.get(key)
              if old_confidence >= confidence:
                  return
          self.info[key] = (confidence, value)
docs: Defines the given value with the given confidence, unless the same
          value is already defined with a higher confidence level.