class SyntaxTree::YARV::InstructionSequence::InstructionList

and other transformations like instruction specialization.
linked list. This is to make it easier to perform peephole optimizations
When the list of instructions is first being created, it’s stored as a

def each(&_blk) 

def each(&_blk)
  return to_enum(__method__) unless block_given?
  each_node { |node| yield node.value }
end

def each_node 

def each_node
  return to_enum(__method__) unless block_given?
  node = head_node
  while node
    yield node, node.value
    node = node.next_node
  end
end

def initialize 

def initialize
  @head_node = nil
  @tail_node = nil
end

def push(instruction) 

def push(instruction)
  node = Node.new(instruction)
  if head_node.nil?
    @head_node = node
    @tail_node = node
  else
    @tail_node.next_node = node
    @tail_node = node
  end
  node
end