code: def symbolic_hint(self, expr: Expr) -> Expr:
      # Substitute all hints into expr, but leave unbacked symints alone
      if not isinstance(expr, Expr):
          assert isinstance(expr, int)
          return expr
      free_symbols = expr.free_symbols
      if not free_symbols:
          return int(expr)
      expr = self.remove_precomputed_replacements(expr)
      return sympy_subs(expr, self.var_to_val)
  
imports: import functools
  import itertools
  import logging
  from typing import Any, Callable, Dict, Iterable, List, Optional, Set, Tuple, Union
  import sympy
  from sympy import Expr
  from torch.fx.experimental.symbolic_shapes import ShapeEnv
  from torch.utils._sympy.functions import FloorDiv, ModularIndexing
  from torch.utils._sympy.value_ranges import bound_sympy
  from .utils import sympy_subs, sympy_symbol, VarRanges
  from .virtualized import V
label_desc: Use image node_id 25 for calling the SizeVarAllocator obj's underlying member method code with example usage: obj.symbolic_hint(expr) and returns: sympy_subs, expr, int