code: def test_reber_classification_exceptions(self):
      with self.assertRaisesRegexp(ValueError, "at least 2 samples"):
          make_reber_classification(n_samples=1)
  
      with self.assertRaises(ValueError):
          make_reber_classification(n_samples=10, invalid_size=-1)
  
      with self.assertRaises(ValueError):
          make_reber_classification(n_samples=10, invalid_size=2)
  
file_path: neupy/tests/datasets/test_reber.py
imports: import math
  import numpy
  from neupy.datasets.reber import avaliable_letters
  from neupy.datasets import make_reber, is_valid_by_reber, make_reber_classification
  from base import BaseTestCase
label_desc: Use image node_id 4 for calling the ReberTestCase obj's underlying member method code with example usage: obj.test_reber_classification_exceptions() without return types