code: def test_bit_scan0():
      assert bit_scan0(-1) is None
      assert bit_scan0(0) == 0
      assert bit_scan0(1) == 1
      assert bit_scan0(-2) == 0
  
file_path: sympy/sympy/external/tests/test_ntheory.py
imports: from itertools import permutations
  from sympy.external.ntheory import bit_scan1, remove, bit_scan0, is_fermat_prp, is_euler_prp, is_strong_prp, gcdext, _lucas_sequence, is_fibonacci_prp, is_lucas_prp, is_selfridge_prp, is_strong_lucas_prp, is_strong_selfridge_prp, is_bpsw_prp, is_strong_bpsw_prp
  from sympy.testing.pytest import raises
label_desc: Use image node_id 2 for calling a global function with example usage: test_bit_scan0() without return types