docs: def _determine_target_color_type(self, y):
          """
          Determines the target color type from the vector y as follows:
  
              - if y is None: only a single color is used
              - if target is auto: determine if y is continuous or discrete
              - otherwise specify supplied target type
  
          This property will be used to compute the colors for each point.
          """
          if y is None:
              self._target_color_type = SINGLE
          elif self.target == "auto":
              # NOTE: See #73 for a generalization to use when implemented
              if len(np.unique(y)) < 10:
                  self._target_color_type = DISCRETE
              else:
                  self._target_color_type = CONTINUOUS
          else:
              self._target_color_type = self.target
  
          if self._target_color_type not in {SINGLE, DISCRETE, CONTINUOUS}:
              raise YellowbrickValueError((
                  "could not determine target color type "
                  "from target='{}' to '{}'"
              ).format(self.target, self._target_color_type))