code: def lookup_precomputed_size(self, expr: Expr) -> sympy.Symbol:
      if (
          isinstance(expr, (int, sympy.Symbol, sympy.Number))
          or expr.is_number
          or expr.is_symbol
      ):
          return expr
      expr = self.remove_precomputed_replacements(expr)
      if expr not in self.precomputed_replacements:
          sym = sympy_symbol(f"ps{len(self.precomputed_replacements)}")
          self.precomputed_replacements[expr] = sym
          self.inv_precomputed_replacements[sym] = expr
      return self.precomputed_replacements[expr]
  
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 34 for calling the SizeVarAllocator obj's underlying member method code with example usage: obj.lookup_precomputed_size(expr) and returns: self, expr