function _fft
  input Integer dir = 1 "Calculation direction: 1 - forward; -1 - backward";
  input Integer m = 3 "Data points = 2^m";
  input Real[:] x = {i for i in 1:8} "Real part of the data";
  input Real[:] y = {0, 0, 0, 0, 0, 0, 0, 0} "Imaginary part of the data";
  output Real[:] x_out = x "Real part of the result";
  output Real[:] y_out = y "Imaginary part of the result";
end _fft;