code: def curvelinear_test1(fig):
      """
      Grid for custom transform.
      """
  
      def tr(x, y):
          return x, y - x
  
      def inv_tr(x, y):
          return x, y + x
  
      grid_helper = GridHelperCurveLinear((tr, inv_tr))
  
      ax1 = fig.add_subplot(
          1, 2, 1, axes_class=Axes, grid_helper=grid_helper
      )
      # ax1 will have ticks and gridlines defined by the given transform (+
      # transData of the Axes).  Note that the transform of the Axes itself
      # (i.e., transData) is not affected by the given transform.
      xx, yy = tr(np.array([3, 6]), np.array([5, 10]))
      ax1.plot(xx, yy)
  
      ax1.set_aspect(1)
      ax1.set_xlim(0, 10)
      ax1.set_ylim(0, 10)
  
      ax1.axis["t"] = ax1.new_floating_axis(0, 3)
      ax1.axis["t2"] = ax1.new_floating_axis(1, 7)
      ax1.grid(True, zorder=0)
  
file_path: matplotlib/galleries/examples/axisartist/demo_curvelinear_grid.py
imports: import matplotlib.pyplot
  import numpy
  from matplotlib.projections import PolarAxes
  from matplotlib.transforms import Affine2D
  from mpl_toolkits.axisartist import Axes, HostAxes, angle_helper
  from mpl_toolkits.axisartist.grid_helper_curvelinear import GridHelperCurveLinear
label_desc: Use image node_id 1 for calling a global function with example usage: curvelinear_test1(fig) and returns: x,  unknown, x,  unknown