code: def test_baseline_precision(self):
      labels = np.array([1, 1, 1, 1, 1, 0, 0, 0, 0, 0])
      scores = np.array([100, 90, 80, 70, 60, 50, 40, 30, 20, 10])
      prec, cutoff = precision_at(labels, scores, top_proportion=1.0)
      self.assertEqual(prec, 0.5)
      self.assertEqual(cutoff, 10)
  
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 3 for calling the Test_precision_at obj's underlying member method code with example usage: obj.test_baseline_precision() without return types