code: def resolver(
          expr, safe=DEFAULT_SAFE, tostr=DEFAULT_TOSTR, scope=DEFAULT_SCOPE,
          besteffort=DEFAULT_BESTEFFORT
  ):
      
  
  
      raise NotImplementedError()
docs: Resolve input expression.
  
      This function is given such as template resolution function. For wrapping
      test for example.
  
      :param str expr: configuration expression to resolve.
      :param bool safe: if True (default), run safely execution context.
      :param bool tostr: format the result.
      :param dict scope: execution scope (contains references to expression
          objects).
      :param bool besteffort: if True (default), try to resolve unknown variable
          name with execution runtime.
      :return: resolved expression.