code: def visit_FunctionDef(self, node):
          
          if (len(node.body) == 1 and
                  isinstance(node.body[0], (ast.Call, ast.Return))):
              ids = self.gather(Identifiers, node.body[0])
              # FIXME : It mark "not inlinable" def foo(foo): return foo
              if node.name not in ids:
                  self.result[node.name] = copy.deepcopy(node)
docs: Determine this function definition can be inlined.