code: def test_slice2len():
      # Test slice length calculation
      assert slice2len(slice(None), 10) == 10
      assert slice2len(slice(11), 10) == 10
      assert slice2len(slice(1, 11), 10) == 9
      assert slice2len(slice(1, 1), 10) == 0
      assert slice2len(slice(1, 11, 2), 10) == 5
      assert slice2len(slice(0, 11, 3), 10) == 4
      assert slice2len(slice(1, 11, 3), 10) == 3
      assert slice2len(slice(None, None, -1), 10) == 10
      assert slice2len(slice(11, None, -1), 10) == 10
      assert slice2len(slice(None, 1, -1), 10) == 8
      assert slice2len(slice(None, None, -2), 10) == 5
      assert slice2len(slice(None, None, -3), 10) == 4
      assert slice2len(slice(None, 0, -3), 10) == 3
      # Start, end are always taken to be relative if negative
      assert slice2len(slice(None, -4, -1), 10) == 3
      assert slice2len(slice(-4, -2, 1), 10) == 2
      # start after stop
      assert slice2len(slice(3, 2, 1), 10) == 0
      assert slice2len(slice(2, 3, -1), 10) == 0
  
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 6 for calling a global function with example usage: test_slice2len() without return types