code: def _is_power2(x):
      if x in (0, 1, 2, 4, 8, 16, 32, 64, 128):
          return True
      if (x & 1) != 0:
          return False
      return _is_power2(x // 2)
  
imports: import numpy
  import mahotas
  import mahotas.convolve
  import mahotas
  from mahotas.convolve import convolve1d, gaussian_filter
  import mahotas._filters
  from mahotas.tests.utils import luispedro_jpg
  import pytest
label_desc: Use image node_id 17 for calling a global function with example usage: _is_power2(x) and returns: _is_power2, True, False