class_docstr: Factorization machine base class.
class_docstr_tok: ["Factorization","machine","base","class","."]
code: def _interaction_val(self, x, combination):
      return functools.reduce(
          lambda x, y: x * y, (x[j] for j in combination)
      )
  
imports: from __future__ import annotations
  import collections
  import functools
  import itertools
  import numpy
  from river import base, optim, utils
  from .base import BaseFM
label_desc: Use image node_id 5 for calling the FM obj's underlying member method code with example usage: obj._interaction_val(x, combination) and returns: functools