class Neuron:
    pass

class NeuronNetwork:
    neurons = []

class Neuron:
    pass

class NeuronNetwork:
    neurons = []

    def __init__(self, rows, columns):
        self.neurons = []
        for row in xrange(rows):
            self.neurons.append([])
            for column in xrange(columns):
                self.neurons[row].append(Neuron())

Create 2D list of Neurons in NeuronNetwork's init
Create 2D list of Neurons in NeuronNetwork's init

  class Neuron:
      pass
  
  class NeuronNetwork:
      neurons = []
  
+     def __init__(self, rows, columns):
+         self.neurons = []
+         for row in xrange(rows):
+             self.neurons.append([])
+             for column in xrange(columns):
+                 self.neurons[row].append(Neuron())
+ 
Create 2D list of Neurons in NeuronNetwork's init
## Code Before:
class Neuron:
    pass

class NeuronNetwork:
    neurons = []

## Instruction:
Create 2D list of Neurons in NeuronNetwork's init
## Code After:
class Neuron:
    pass

class NeuronNetwork:
    neurons = []

    def __init__(self, rows, columns):
        self.neurons = []
        for row in xrange(rows):
            self.neurons.append([])
            for column in xrange(columns):
                self.neurons[row].append(Neuron())
