code: def instruction_size(self, insn_addr):
          
  
          for b in self.blocks:
              block = self._get_block(b.addr, size=b.size, byte_string=b.bytestr)
              if insn_addr in block.instruction_addrs:
                  index = block.instruction_addrs.index(insn_addr)
                  if index == len(block.instruction_addrs) - 1:
                      # the very last instruction
                      size = block.addr + block.size - insn_addr
                  else:
                      size = block.instruction_addrs[index + 1] - insn_addr
                  return size
  
          return None
docs: Get the size of the instruction specified by `insn_addr`.
  
          :param int insn_addr: Address of the instruction
          :return: Size of the instruction in bytes, or None if the instruction is not found.
          :rtype: int