Draws a multi dimensional dispersion chart, each color corresponds
        to a different target variable.

def draw_multi_dispersion_chart(self, nan_locs):
        """Draws a multi dimensional dispersion chart, each color corresponds
        to a different target variable.
        """
        for index, nan_values in enumerate(nan_locs):
            label, nan_locations = nan_values

            # if features passed in then, label as such
            if self.classes_ is not None:
                label = self.classes_[index]

            color = self.colors[index]

            x_, y_ = list(zip(*nan_locations))
            self.ax.scatter(x_, y_, alpha=self.alpha, marker=self.marker, color=color, label=label)