code: def fft(x):
      """Fast Fourier transform.
  
      Args:
          x (tuple): ``(real, imag)`` where ``real`` is a
              :class:`~chainer.Variable` or an :ref:`ndarray` storing the real
              part and ``imag`` is a :class:`~chainer.Variable` or an
              :ref:`ndarray` storing the imaginary part.
  
      Returns:
          tuple: Returns ``(ry, iy)`` where ``ry`` is the real part of
          the result and ``iy`` is the imaginary part of the result.
  
      .. note::
         Currently this function supports a tuple as input. It will support a
         complex numbers directly in the future.
  
      """
      real, imag = x
      return FFT("fft").apply((real, imag))
  
file_path: chainer/chainer/functions/math/fft.py
imports: from chainer import backend
  from chainer import function_node
  from chainer.utils import type_check
label_desc: Use image node_id 1 for calling a global function with example usage: fft(x) and returns: FFT