code: def test_roc_curve_str(self):
      y = turicreate.SArray(["a", "b", "a", "b"])
      yhat = turicreate.SArray([0.1, 0.2, 0.3, 0.4])
  
      res = turicreate.toolkits.evaluation.roc_curve(y, yhat)
      points = res[["fpr", "tpr"]].unique().sort(["fpr", "tpr"])
      self.assertTrue(all(res["tpr"] >= 0) and all(res["tpr"] <= 1))
      self.assertTrue(all(res["fpr"] >= 0) and all(res["fpr"] <= 1))
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  import unittest
  import turicreate
  from turicreate.toolkits._main import ToolkitError
  import math
  from numpy import inf
  import numpy
label_desc: Use image node_id 11 for calling the MetricsTest obj's underlying member method code with example usage: obj.test_roc_curve_str() without return types