code: def test_interpolation(self):
      x = torch.linspace(0.01, 1, 100).unsqueeze(1)
      grid = torch.linspace(-0.05, 1.05, 50).unsqueeze(1)
      indices, values = Interpolation().interpolate(grid, x)
      indices = indices.squeeze_(0)
      values = values.squeeze_(0)
      test_func_grid = grid.squeeze(1).pow(2)
      test_func_x = x.pow(2).squeeze(-1)
  
      interp_func_x = left_interp(
          indices, values, test_func_grid.unsqueeze(1)
      ).squeeze()
  
      self.assertTrue(approx_equal(interp_func_x, test_func_x))
  
file_path: gpytorch/test/utils/test_interpolation.py
imports: import unittest
  import torch
  from linear_operator.utils.interpolation import left_interp
  from gpytorch.test.utils import approx_equal
  from gpytorch.utils.interpolation import Interpolation
label_desc: Use image node_id 1 for calling the TestCubicInterpolation obj's underlying member method code with example usage: obj.test_interpolation() without return types