def fft():
    raise NotImplementedError


def ifft():
    raise NotImplementedError


def fftn():
    raise NotImplementedError


def ifftn():
    raise NotImplementedError


def rfft():
    raise NotImplementedError


def irfft():
    raise NotImplementedError


def rfftn():
    raise NotImplementedError


def irfftn():
    raise NotImplementedError


def hfft():
    raise NotImplementedError


def ihfft():
    raise NotImplementedError


def fftfreq():
    raise NotImplementedError


def rfftfreq():
    raise NotImplementedError


def fftshift():
    raise NotImplementedError


def ifftshift():
    raise NotImplementedError
