code: def _matmul(a, b, xp):
      if hasattr(
          xp, "matmul"
      ):  # numpy.matmul is supported from version 1.10.0
          return xp.matmul(a, b)
      else:
          return xp.einsum("bij,bjk->bik", a, b)
  
imports: import numpy
  from chainer import backend
  from chainer import function_node
  from chainer.utils import argument
  from chainer.utils import type_check
label_desc: Use image node_id 2 for calling a global function with example usage: _matmul(a, b, xp) and returns: xp, xp