class_docstr: Debug renderer implemented using Matplotlib.
  
  Extends ``MplRenderer`` to add extra information to help in debugging such as markers, arrows,
  text, etc.
code: def quad_numbers(
      self,
      x: ArrayLike,
      y: ArrayLike,
      z: ArrayLike,
      ax: Axes | int = 0,
      color: str = "blue",
  ) -> None:
      ax = self._get_ax(ax)
      x, y = self._grid_as_2d(x, y)
      z = np.asarray(z)
      ny, nx = z.shape
      for j in range(1, ny):
          for i in range(1, nx):
              quad = i + j * nx
              xmid = x[j - 1 : j + 1, i - 1 : i + 1].mean()
              ymid = y[j - 1 : j + 1, i - 1 : i + 1].mean()
              ax.text(
                  xmid,
                  ymid,
                  str(quad),
                  ha="center",
                  va="center",
                  color=color,
                  clip_on=True,
              )
  
imports: from __future__ import annotations
  from collections.abc import Sequence
  import io
  from typing import TYPE_CHECKING, Any, cast
  import matplotlib.collections
  import matplotlib.pyplot
  import numpy
  from contourpy import FillType, LineType
  from contourpy.convert import convert_filled, convert_lines
  from contourpy.enum_util import as_fill_type, as_line_type
  from contourpy.util.mpl_util import filled_to_mpl_paths, lines_to_mpl_paths
  from contourpy.util.renderer import Renderer
label_desc: Use image node_id 6 for calling the MplDebugRenderer obj's underlying member method code with example usage: obj.quad_numbers(x, y, z, ax, color) without return types