code: def generate_inputs(self):
      shape = self.shape
  
      # sample x such that x.std >= min_std
      min_std = 0.02
      retry = 0
      while True:
          x = numpy.random.uniform(-1, 1, shape).astype(self.dtype)
          x_groups = x.reshape(shape[0], self.groups, -1)
          if x_groups.std(axis=2).min() >= min_std:
              break
          retry += 1
          assert retry <= 20, "Too many retries to generate inputs"
  
      return (x,)
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import links
  from chainer import testing
  from chainer.testing import attr
label_desc: Use image node_id 4 for calling the GroupNormalizationTest obj's underlying member method code with example usage: obj.generate_inputs() and returns: x