code: def test_parameters_expr_and_constraints():
      """Regression tests for GitHub Issue #265. Test that parameters are re-
      evaluated if they have bounds and expr.
  
      """
      p = lmfit.Parameters()
      p.add(lmfit.Parameter("a", 10, True))
      p.add(lmfit.Parameter("b", 10, True, 0, 20))
  
      assert_allclose(p["b"].min, 0)
      assert_allclose(p["b"].max, 20)
  
      p["a"].expr = "2 * b"
      assert_allclose(p["a"].value, 20)
  
      p["b"].value = 15
      assert_allclose(p["b"].value, 15)
      assert_allclose(p["a"].value, 30)
  
      p["b"].value = 30
      assert_allclose(p["b"].value, 20)
      assert_allclose(p["a"].value, 40)
  
imports: from copy import copy, deepcopy
  import os
  import pickle
  import numpy
  from numpy.testing import assert_allclose
  import pytest
  import lmfit
  from lmfit.models import VoigtModel
label_desc: Use image node_id 28 for calling a global function with example usage: test_parameters_expr_and_constraints() without return types