build_layer.py

def build_layer(self):
      new_layer = []

      if len(self.layer) % 2 == 1:
          self.layer.append(self.layer[-1])

      for i in range(0, len(self.layer), 2):
          left = self.layer[i]
          right = self.layer[i+1]
          parent = Node(left.hash + right.hash)

          left.parent = parent
          left.sibling = right
          left.position = "left"

          right.parent = parent
          right.sibling = left
          right.position = "right"

          parent.left = left
          parent.right = right

          new_layer.append(parent)

      self.layer = new_layer