code: def test_no_tp_at_50(self):
      y_true = np.array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
      y_score = np.array(
          [1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1]
      )
      tps = tp_at(y_true, y_score, top_proportion=0.5)
      self.assertEqual(tps, 0)
  
imports: from unittest import TestCase
  from sklearn_evaluation.metrics import precision_at, labels_at, tp_at, fp_at
  import numpy
  from numpy import nan
label_desc: Use image node_id 5 for calling the Test_tp_at obj's underlying member method code with example usage: obj.test_no_tp_at_50() without return types