input: Write a python function to create an instance of PcaPlotVector and test its methods.
  assert len(pca_plot_vector) == expected_length
  assert pca_plot_vector[0] == expected_first_element
  assert list(iter(pca_plot_vector)) == expected_full_list
  assert pca_plot_vector.getObservation() == expected_observation_value
  assert pca_plot_vector.getSingularValue() == expected_singular_value
output: def test_pca_plot_vector():
      class PcaPlotVector:
          def __init__(self, data, observation, singular_value):
              self.data = data
              self.observation = observation
              self.singular_value = singular_value
  
          def __len__(self):
              return len(self.data)
  
          def __getitem__(self, index):
              return self.data[index]
  
          def __iter__(self):
              return iter(self.data)
  
          def getObservation(self):
              return self.observation
  
          def getSingularValue(self):
              return self.singular_value
  
      # Example data and expected values for testing
      example_data = [1.0, 2.0, 3.0]
      example_observation = 'Observation1'
      example_singular_value = 2.5
  
      expected_length = 3
      expected_first_element = 1.0
      expected_full_list = [1.0, 2.0, 3.0]
      expected_observation_value = 'Observation1'
      expected_singular_value = 2.5
  
      pca_plot_vector = PcaPlotVector(example_data, example_observation, example_singular_value)
  
      # Assertions to test PcaPlotVector
      assert len(pca_plot_vector) == expected_length
      assert pca_plot_vector[0] == expected_first_element
      assert list(iter(pca_plot_vector)) == expected_full_list
      assert pca_plot_vector.getObservation() == expected_observation_value
      assert pca_plot_vector.getSingularValue() == expected_singular_value