code: def plot_point(self, x, y, visible=True, color='black', size=5):
          
          xp = (self.px_x * (x - self.x_min)) / self.x_tick
          yp = (self.px_y * (self.y_max - y)) / self.y_tick
          coord = 50 + xp, 50 + yp
  
          if visible:
              # divide down to an appropriate size
              size = int(size/2) if int(size/2) > 1 else 1
              x, y = coord
  
              self.canvas.create_oval(
                  x-size, y-size,
                  x+size, y+size,
                  fill=color
              )
  
          return coord
docs: Places a single point on the grid
  
          :param x: the x coordinate
          :param y: the y coordinate
          :param visible: True if the individual point should be visible
          :param color: the color of the point
          :param size: the point size in pixels
          :return: The absolute coordinates as a tuple