code: def func(self, xp, a):
      return xp.expm1(a)
  
imports: import chainer
  import chainerx
  import numpy
  from chainerx_tests import math_utils
  from chainerx_tests import op_utils
label_desc: Use image node_id 1 for calling the TestExpm1 obj's underlying member method code with example usage: obj.func(xp, a) and returns: xp