code: def _refine_reim(expr, assumptions):
      # Helper function for refine_re & refine_im
      expanded = expr.expand(complex=True)
      if expanded != expr:
          refined = refine(expanded, assumptions)
          if refined != expanded:
              return refined
      # Best to leave the expression as is
      return None
  
file_path: sympy/sympy/assumptions/refine.py
imports: from __future__ import annotations
  from typing import Callable
  from sympy.core import S, Add, Expr, Basic, Mul, Pow, Rational
  from sympy.core.logic import fuzzy_not
  from sympy.logic.boolalg import Boolean
  from sympy.assumptions import ask, Q
label_desc: Use image node_id 8 for calling a global function with example usage: _refine_reim(expr, assumptions) and returns: None, refined