code: def _make_y_title(self):
          
          if self._y_title:
              yc = self.margin_box.top + self.view.height / 2
              for i, title_line in enumerate(self._y_title, 1):
                  text = self.svg.node(
                      self.nodes['title'],
                      'text',
                      class_='title',
                      x=self._legend_at_left_width,
                      y=i * (self.style.title_font_size + self.spacing) + yc
                  )
                  text.attrib['transform'] = "rotate(%d %f %f)" % (
                      -90, self._legend_at_left_width, yc
                  )
                  text.text = title_line
docs: Make the Y-Axis title