class_docstr: Profiler whose :meth:`profile` method is an evaluation of a precomputed expression.
  
  This type of profiler is useful for optimization and analysis.
  For example, to find the best model size is equivalent to find the minimum value of the expression.
  Users can also compute the mathematical expression for a distribution of model samples.
code: def profile(self, sample: Sample) -> float:
      if isinstance(self.expression, (float, int)):
          return float(self.expression)
      else:
          return self.expression.evaluate(sample)
  
file_path: nni/nni/nas/profiler/profiler.py
imports: from __future__ import annotations
  from nni.mutable import Sample
  from nni.mutable.symbol import SymbolicExpression
  from nni.nas.space import BaseModelSpace
label_desc: Use image node_id 1 for calling the ExpressionProfiler obj's underlying member method code with example usage: obj.profile(sample) and returns: float, self