code: def _sigmoid(x, xp=numpy):
      half = x.dtype.type(0.5)
      return xp.tanh(x * half) * half + half
  
imports: import numpy
  import six
  from chainer import backend
  from chainer.backends import cuda
  from chainer.backends import intel64
  from chainer import function
  from chainer import function_node
  from chainer.utils import type_check
  import chainerx
label_desc: Use image node_id 2 for calling a global function with example usage: _sigmoid(x, xp) and returns: unknown