code: def write_block(self, block_, body):
      
      self.write('for ; πF.State() >= 0; πF.PopCheckpoint() {')
      with self.indent_block():
        self.write('switch πF.State() {')
        self.write('case 0:')
        for checkpoint in block_.checkpoints:
          self.write_tmpl('case $state: goto Label$state', state=checkpoint)
        self.write('default: panic("unexpected function state")')
        self.write('}')
        # Assume that body is aligned with goto labels.
        with self.indent_block(-1):
          self.write(body)
      self.write('}')
docs: Outputs the boilerplate necessary for code blocks like functions.
  
      Args:
        block_: The Block object representing the code block.
        body: String containing Go code making up the body of the code block.