code: def direct_shift(x, a, period=None):
      n = len(x)
      if period is None:
          k = fftfreq(n) * 1j * n
      else:
          k = fftfreq(n) * 2j * pi / period * n
      return ifft(fft(x) * exp(k * a)).real
  
imports: from numpy.testing import assert_equal, assert_almost_equal, assert_array_almost_equal
  from scipy.fftpack import diff, fft, ifft, tilbert, itilbert, hilbert, ihilbert, shift, fftfreq, cs_diff, sc_diff, ss_diff, cc_diff
  import numpy
  from numpy import arange, sin, cos, pi, exp, tanh, sum, sign
  from numpy.random import random
label_desc: Use image node_id 6 for calling a global function with example usage: direct_shift(x, a, period) and returns: ifft