code: def _dict_from_expr_if_gens(expr, opt):
      """Transform an expression into a multinomial form given generators."""
      (poly,), gens = _parallel_dict_from_expr_if_gens((expr,), opt)
      return poly, gens
  
imports: from __future__ import annotations
  from sympy.external.gmpy import GROUND_TYPES
  from sympy.core import S, Add, Mul, Pow, Eq, Expr, expand_mul, expand_multinomial
  from sympy.core.exprtools import decompose_power, decompose_power_rat
  from sympy.core.numbers import _illegal
  from sympy.polys.polyerrors import PolynomialError, GeneratorsError
  from sympy.polys.polyoptions import build_options
  import re
label_desc: Use image node_id 9 for calling a global function with example usage: _dict_from_expr_if_gens(expr, opt) and returns: poly,  gens