code: def ihilbert(x):
      """
      Return inverse Hilbert transform of a periodic sequence x.
  
      If ``x_j`` and ``y_j`` are Fourier coefficients of periodic functions x
      and y, respectively, then::
  
        y_j = -sqrt(-1)*sign(j) * x_j
        y_0 = 0
  
      """
      return -hilbert(x)
  
file_path: catboost/contrib/python/scipy/py3/scipy/fftpack/pseudo_diffs.py
imports: from numpy import pi, asarray, sin, cos, sinh, cosh, tanh, iscomplexobj
  from .None import convolve
  from scipy.fft._pocketfft.helper import _datacopied
label_desc: Use image node_id 5 for calling a global function with example usage: ihilbert(x) and returns: unknown