why "lambda x: x ()()()()" works in Python? : I put several '()' after a lambda, seems Python ignores them rather than throwing error. Why? Thanks.

my code as

    >>> lambda x: x ()()()()
    <function <lambda> at 0x105ca7ed8>
    >>> lambda x: x (1)(2)(dfdf)()
    <function <lambda> at 0x105cae578>



