code: def test_force_backprop_mode():
      with chainerx.backprop_scope(
          "bp1"
      ) as bp1, chainerx.backprop_scope("bp2") as bp2:
          with chainerx.no_backprop_mode():
              assert not chainerx.is_backprop_required()
              assert not chainerx.is_backprop_required(bp1)
              assert not chainerx.is_backprop_required(bp2)
  
              with chainerx.force_backprop_mode():
                  assert chainerx.is_backprop_required()
                  assert chainerx.is_backprop_required(bp1)
                  assert chainerx.is_backprop_required(bp2)
              assert not chainerx.is_backprop_required()
              assert not chainerx.is_backprop_required(bp1)
              assert not chainerx.is_backprop_required(bp2)
  
              with chainerx.force_backprop_mode(
                  chainerx.get_default_context()
              ):
                  assert chainerx.is_backprop_required()
                  assert chainerx.is_backprop_required(bp1)
                  assert chainerx.is_backprop_required(bp2)
              assert not chainerx.is_backprop_required()
              assert not chainerx.is_backprop_required(bp1)
              assert not chainerx.is_backprop_required(bp2)
  
              with chainerx.force_backprop_mode(bp1):
                  assert not chainerx.is_backprop_required()
                  assert chainerx.is_backprop_required(bp1)
                  assert not chainerx.is_backprop_required(bp2)
              assert not chainerx.is_backprop_required()
              assert not chainerx.is_backprop_required(bp1)
              assert not chainerx.is_backprop_required(bp2)
  
              with chainerx.force_backprop_mode((bp1, bp2)):
                  assert not chainerx.is_backprop_required()
                  assert chainerx.is_backprop_required(bp1)
                  assert chainerx.is_backprop_required(bp2)
              assert not chainerx.is_backprop_required()
              assert not chainerx.is_backprop_required(bp1)
              assert not chainerx.is_backprop_required(bp2)
  
          with chainerx.force_backprop_mode():
              assert chainerx.is_backprop_required()
              assert chainerx.is_backprop_required(bp1)
              assert chainerx.is_backprop_required(bp2)
  
imports: import pytest
  import chainerx
label_desc: Use image node_id 2 for calling a global function with example usage: test_force_backprop_mode() without return types