code: def test_calc_slicedefs():
      # Check get_segments routine.  The tests aren't well organized because I
      # wrote them after the code.  We live and (fail to) learn
      segments, out_shape, new_slicing = calc_slicedefs(
          (1,), (10,), 4, 7, "F", _never
      )
      assert segments == [[11, 4]]
      assert new_slicing == ()
      assert out_shape == ()
      assert calc_slicedefs(
          (slice(None),), (10,), 4, 7, "F", _never
      ) == (
          [[7, 40]],
          (10,),
          (),
      )
      assert calc_slicedefs((slice(9),), (10,), 4, 7, "F", _never) == (
          [[7, 36]],
          (9,),
          (),
      )
      assert calc_slicedefs(
          (slice(1, 9),), (10,), 4, 7, "F", _never
      ) == (
          [[11, 32]],
          (8,),
          (),
      )
      # Two dimensions, single slice
      assert calc_slicedefs((0,), (10, 6), 4, 7, "F", _never) == (
          [[7, 4], [47, 4], [87, 4], [127, 4], [167, 4], [207, 4]],
          (6,),
          (),
      )
      assert calc_slicedefs((0,), (10, 6), 4, 7, "C", _never) == (
          [[7, 6 * 4]],
          (6,),
          (),
      )
      # Two dimensions, contiguous not full
      assert calc_slicedefs(
          (1, slice(1, 5)), (10, 6), 4, 7, "F", _never
      ) == (
          [[51, 4], [91, 4], [131, 4], [171, 4]],
          (4,),
          (),
      )
      assert calc_slicedefs(
          (1, slice(1, 5)), (10, 6), 4, 7, "C", _never
      ) == (
          [[7 + 7 * 4, 16]],
          (4,),
          (),
      )
      # With full slice first
      assert calc_slicedefs(
          (slice(None), slice(1, 5)), (10, 6), 4, 7, "F", _never
      ) == (
          [[47, 160]],
          (10, 4),
          (),
      )
      # Check effect of heuristic on calc_slicedefs
      # Even integer slices can generate full when heuristic says so
      assert calc_slicedefs(
          (1, slice(None)), (10, 6), 4, 7, "F", _always
      ) == (
          [[7, 10 * 6 * 4]],
          (10, 6),
          (1, slice(None)),
      )
      # Except when last
      assert calc_slicedefs(
          (slice(None), 1), (10, 6), 4, 7, "F", _always
      ) == (
          [[7 + 10 * 4, 10 * 4]],
          (10,),
          (),
      )
  
imports: import time
  from functools import partial
  from io import BytesIO
  from itertools import product
  from threading import Lock, Thread
  import numpy
  import pytest
  from numpy.testing import assert_array_equal
  from ..fileslice import _positive_slice, _simple_fileslice, calc_slicedefs, canonical_slicers, fileslice, fill_slicer, is_fancy, optimize_read_slicers, optimize_slicer, predict_shape, read_segments, slice2len, slice2outax, slicers2segments, strided_scalar, threshold_heuristic
label_desc: Use image node_id 16 for calling a global function with example usage: test_calc_slicedefs() without return types