class BasicBlock:
   """ Uninterrupted sequence of instructions. """
   def __init__(self, name):
      self.name = name
      self.instructions = []
   def __repr__(self):
      return 'BasicBlock {0}'.format(self.name)
   def addInstruction(self, i):
      i.parent = self
      self.instructions.append(i)
   addIns = addInstruction

   def replaceInstruction(self, i1, i2):
      idx = self.instructions.index(i1)
      i1.parent = None
      i1.delete()
      i2.parent = self
      self.instructions[idx] = i2

   def removeInstruction(self, i):
      i.parent = None
      self.instructions.remove(i)

   def getInstructions(self):
        return self.instructions

   def setInstructions(self, ins):
      for i in self.instructions:
         i.parent = None
      self.instructions = ins
      for i in self.instructions:
         i.parent = self
   Instructions = property(getInstructions, setInstructions)

   def getLastIns(self):
      return self.instructions[-1]
   LastInstruction = property(getLastIns)
   @property
   def Empty(self):
      return len(self.instructions) == 0
   @property
   def FirstInstruction(self):
      return self.instructions[0]
   FirstIns = FirstInstruction
   def getSuccessors(self):
      if not self.Empty:
         i = self.LastInstruction
         print(i)
         return i.Targets
      return []
   Successors = property(getSuccessors)
   def getPredecessors(self):
      preds = []
      for bb in self.parent.BasicBlocks:
         if self in bb.Successors:
            preds.append(bb)
      return preds
   Predecessors = property(getPredecessors)