code: def test__fix0():
      # Test routine to fix possible zero TR in affine
      assert_array_equal(
          _fix0(np.diag([1, 2, 3, 1])), np.diag([1, 2, 3, 1])
      )
      assert_array_equal(
          _fix0(np.diag([0, 2, 3, 1])), np.diag([1, 2, 3, 1])
      )
      assert_array_equal(
          _fix0(np.diag([1, 0, 3, 1])), np.diag([1, 1, 3, 1])
      )
      assert_array_equal(
          _fix0(np.diag([1, 2, 0, 1])), np.diag([1, 2, 1, 1])
      )
      aff = [[1, 0, 0, 10], [0, 0, 0, 11], [0, 0, 0, 1]]
      assert_array_equal(_fix0(aff), aff)
      aff = [[1, 0, 0, 10], [0, 2, 0, 11], [0, 0, 0, 12], [0, 0, 0, 1]]
      assert_array_equal(
          _fix0(aff),
          [[1, 0, 0, 10], [0, 2, 0, 11], [0, 0, 1, 12], [0, 0, 0, 1]],
      )
      eps = np.finfo(np.float64).eps
      aff[2][2] = eps
      assert_array_equal(_fix0(aff), aff)
  
imports: from copy import copy
  from types import SimpleNamespace
  import numpy
  from ..coordinate_map import AffineTransform, AxisError, CoordinateMap, CoordMapMaker, CoordMapMakerError, _as_coordinate_map, _fix0, append_io_dim, axmap, compose, drop_io_dim, equivalent, input_axis_index, io_axis_indices, orth_axes, product, shifted_domain_origin, shifted_range_origin
  from ..coordinate_system import CoordinateSystem, CoordinateSystemError, CoordSysMaker
  import pytest
  from numpy.testing import assert_almost_equal, assert_array_equal
label_desc: Use image node_id 33 for calling a global function with example usage: test__fix0() without return types