code: def _implicit_otor(other, reg):
      nf = other.shape[1]
      regmat = np.identity(nf)
      regmat *= reg
      Ot = other.T
      OtO = Ot @ other
      OtO += regmat
      return OtO
  
imports: import logging
  from collections import namedtuple
  import numpy
  from numba import njit, prange
  from csr import CSR
  from seedbank import numpy_rng
  from .bias import Bias
  from .mf_common import MFPredictor
  from ..data import sparse_ratings
  from ..None import util
  from ..math.solve import _dposv
label_desc: Use image node_id 8 for calling a global function with example usage: _implicit_otor(other, reg) and returns: OtO