code: def _test_global_traversal(trav):
      zero_all_symbols = trav(zero_symbols)
  
      assert zero_all_symbols(Basic(x, y, Basic(x, z))) == Basic(
          S(0), S(0), Basic(S(0), S(0))
      )
  
imports: from sympy.strategies.traverse import top_down, bottom_up, sall, top_down_once, bottom_up_once, basic_fns
  from sympy.strategies.rl import rebuild
  from sympy.strategies.util import expr_fns
  from sympy.core.add import Add
  from sympy.core.basic import Basic
  from sympy.core.numbers import Integer
  from sympy.core.singleton import S
  from sympy.core.symbol import Str, Symbol
  from sympy.abc import x, y, z
label_desc: Use image node_id 5 for calling a global function with example usage: _test_global_traversal(trav) without return types