code: def ddm_imatmul(
      a: list[list[R]],
      b: Sequence[Sequence[R]],
      c: Sequence[Sequence[R]],
  ) -> None:
      """a += b @ c"""
      cT = list(zip(*c))
  
      for bi, ai in zip(b, a):
          for j, cTj in enumerate(cT):
              ai[j] = sum(map(mul, bi, cTj), ai[j])
  
file_path: sympy/sympy/polys/matrices/dense.py
imports: from __future__ import annotations
  from operator import mul
  from .exceptions import DMShapeError, DMDomainError, DMNonInvertibleMatrixError, DMNonSquareMatrixError
  from typing import Sequence, TypeVar
  from sympy.polys.matrices._typing import RingElement
label_desc: Use image node_id 7 for calling a global function with example usage: ddm_imatmul(a, b, c) without return types