code: def downsampling_by_2(x, filterKernel):
      """A helper function that downsamples the audio by half. It is used in CQT2010 and CQT2010v2
  
      Parameters
      ----------
      x : torch.Tensor
          The input waveform in ``torch.Tensor`` type with shape ``(batch, 1, len_audio)``
  
      filterKernel : str
          Filter kernel in ``torch.Tensor`` type with shape ``(1, 1, len_kernel)``
  
      Returns
      -------
      torch.Tensor
          The downsampled waveform
  
      Examples
      --------
      >>> x_down = downsampling_by_2(x, filterKernel)
      """
  
      return downsampling_by_n(x, filterKernel, 2)
  
imports: import sys
  import torch
  from torch.nn.functional import conv1d, fold
  import numpy
  from time import time
  import math
  from scipy.signal import get_window
  from scipy import signal
  from scipy.fftpack import fft
  import warnings
  from nnAudio.librosa_functions import *
label_desc: Use image node_id 7 for calling a global function with example usage: downsampling_by_2(x, filterKernel) and returns: downsampling_by_n