old_contents: from preprocessing import *
  import numpy as np
  
  class Instance:
      # This is a simple encapsulation of a `input signal : output signal`
      # pair in our training set.
      def __init__(self, features, target = None ):
          self.features = np.array(features)
          
          if target:
              self.targets  = np.array(target)
          else:
              self.targets  = None
  #endclass Instance
  
  
new_contents: from preprocessing import *
  import numpy as np
  
  class Instance:
      # This is a simple encapsulation of a `input signal : output signal`
      # pair in our training set.
      def __init__(self, features, target = None ):
          self.features = np.array(features)
          
          if target != None:
              self.targets  = np.array(target)
          else:
              self.targets  = None
  #endclass Instance
  
  
subject: check whether the targets are equal to None