def METHOD_NAME(self):
    # maybe[string]
    n1 = ast.NamedType('string')
    print(n1)
    n2 = ast.ParameterizedType('Optional', [n1])
    print(n2)
    n3 = ast.ParameterizedType('Dict', [n1, ast.NamedType('int')])
    print(n3)