code: def read_code(self, address, size=1):
          
          assert address < len(self.bytecode)
          value = self.bytecode[address:address + size]
          if len(value) < size:
              value += '\x00' * (size - len(value))  # pad with null (spec)
          return value
docs: Read size byte from bytecode.
          If less than size bytes are available result will be pad with \x00