问Python模块无法检测"if“或"for”

EN

class SyntaxChecker(ast.NodeVisitor):

    def check(self, syntax):
        tree = ast.parse(syntax)
        print(ast.dump(tree), syntax)
        self.visit(tree)

    def visit_Call(self, node):
        print('Called for Call', ast.dump(node))
        if isinstance(node.func, ast.Call) and node.func.id not in allowed_functions:
            raise CodeError("%s is not an allowed function!"%node.func.id)
        elif isinstance(node.func, ast.Attribute) and node.func.value.id not in allowed_classes:
            raise CodeError('{0} is not calling an allowed class'.format(node.func.value.id))
        elif isinstance(node.func, ast.Name) and node.func.id in allowed_classes:
            raise CodeError('You are not allowed to instantiate any class, {0}'.format(node.func.id))
        else:
            ast.NodeVisitor.generic_visit(self, node)

    def visit_Assign(self, node):
        print('Called for Assign', ast.dump(node))
        ast.NodeVisitor.generic_visit(self, node)

    def visit_Attribute(self, node):
        print('Called for Attribute', ast.dump(node))
        if node.value.id not in allowed_classes:
            raise CodeError('"{0}" is not an allowed class'.format(node.value.id))
        elif node.value.id in allowed_classes and isinstance(node.ctx, ast.Store):
            raise CodeError('Trying to change something in a pre-defined class, "{0}" in "{1}"'.format(node.attr, node.value.id))
        else:
            ast.NodeVisitor.generic_visit(self, node)

    def visit_Expr(self, node):
        print('Called for Expr', ast.dump(node))
        ast.NodeVisitor.generic_visit(self, node)

    def visit_Name(self, node):
        print('Called for Name', ast.dump(node))
        if isinstance(node.ctx, ast.Store) and node.id in allowed_classes:
            raise CodeError('Trying to change a pre-defined class, {0}'.format(node.id))
        elif isinstance(node.ctx, ast.Load) and node.id not in safe_names and node.id not in allowed_functions and node.id not in allowed_classes:
            raise CodeError('"{0}" function is not allowed'.format(node.id))
        else:
            ast.NodeVisitor.generic_visit(self, node)

    def generic_visit(self, node):
        print('Called for generic', ast.dump(node))        
        if type(node).__name__ not in allowed_node_types:
            raise CodeError("%s is not allowed!"%type(node).__name__)
        else:
            ast.NodeVisitor.generic_visit(self, node)

if __name__ == '__main__':
    # Check whole file
    x = SyntaxChecker()
    code = open(sys.argv[1], 'r').read()
    try:
        x.check(code)
    except CodeError as e:
        print(repr(e))

    # Or check line by line, considering multiline statements
    code = ''
    for line in open(sys.argv[1], 'r'):
        line = line.strip()
        if line:
            code += line
            try:
                print('[{0}]'.format(code))
                x.check(code)
                code = ''
            except CodeError as e:
                print(repr(e))
                break
            except SyntaxError as e:
                print('********Feeding next line', repr(e))

for j in A.b():
    print('hey')