code: def check_type_forward(self, in_types):
      type_check._argname(in_types, ("n", "x"))
      n_type, x_type = in_types
  
      type_check.expect(
          n_type.dtype.kind == "i",
          x_type.dtype.kind == "f",
      )
  
file_path: chainer/chainer/functions/math/polygamma.py
imports: from chainer.backends import cuda
  from chainer import function_node
  from chainer import utils
  from chainer.utils import type_check
label_desc: Use image node_id 2 for calling the PolyGamma obj's underlying member method code with example usage: obj.check_type_forward(in_types) without return types