code: def btc_witness_script_serialize(_stack):
      
      stack = _stack
      if encoding.json_is_base(_stack, 16):
          # hex-to-bin all hex strings 
          stack = encoding.json_changebase(_stack, lambda x: binascii.unhexlify(x))
  
      return encoding.safe_hexlify(_btc_witness_serialize_unit(len(stack)) + ''.join(map(lambda stack_unit: _btc_witness_serialize_unit(stack_unit), stack)))
docs: Given a deserialized witness script stack (i.e. the input-specific witness, as an array of
      Nones, ints, and strings), turn it back into a hex-encoded script