code: def execute_function(self, func, *nargs, **kwargs):
          
          # makes a copy of the func
          import types
          fn = types.FunctionType(func.func_code,
                                  func.func_globals.copy(),
                                  name=func.func_name,
                                  argdefs=func.func_defaults,
                                  closure=func.func_closure)
          fn.func_globals.update(self.globals)
  
          error_class = Exception if config.catch_rex_errors else None
  
          try:
              return fn(*nargs, **kwargs)
          except RexError:
              raise
          except error_class as e:
              from inspect import getfile
  
              stack = traceback.format_exc()
              filename = getfile(func)
  
              raise RexError("Failed to exec %s:\n\n%s" % (filename, stack))
docs: Execute a function object within the execution context.
          @returns The result of the function call.