code: def test_conf_scope_can_access_fallback():
      @ConfigScope
      def conf_scope(a):
          answer = 2 * a
  
      cfg = conf_scope(fallback={"a": 21})
      assert cfg["answer"] == 42
  
imports: import pytest
  import sacred.optional
  from sacred.config.config_scope import ConfigScope, dedent_function_body, dedent_line, get_function_body, is_empty_or_comment
  from sacred.config.custom_containers import DogmaticDict, DogmaticList
label_desc: Use image node_id 16 for calling a global function with example usage: test_conf_scope_can_access_fallback() without return types