code: def pack(self, value, pb_type):
      if (
          pb_type is FieldDescriptor.TYPE_INT32
          or pb_type is FieldDescriptor.TYPE_INT64
      ):
          return struct.pack("<i", value)
      elif (
          pb_type is FieldDescriptor.TYPE_UINT32
          or pb_type is FieldDescriptor.TYPE_ENUM
          or pb_type is FieldDescriptor.TYPE_UINT64
      ):
          return struct.pack("<I", value)
      elif pb_type is FieldDescriptor.TYPE_BOOL:
          return struct.pack("<i", (int)(value))
      elif pb_type is FieldDescriptor.TYPE_FLOAT:
          return struct.pack("<f", value)
      elif pb_type is FieldDescriptor.TYPE_DOUBLE:
          return struct.pack("<d", value)
      elif pb_type is TYPE_UINT16:
          return struct.pack("<H", value)
      elif (
          pb_type is FieldDescriptor.TYPE_STRING
          or pb_type is FieldDescriptor.TYPE_BYTES
      ):
          if isinstance(value, str):
              value = bytes(value.encode("utf-8"))
          length = self.str_raw_len(value)
          if length == 0:
              return b""
          pack_length = self.str_pack_len(value)
          empty_len = pack_length - length
          while empty_len > 0:
              value += b"\0"
              empty_len -= 1
          return struct.pack("<" + str(pack_length) + "s", value)
      else:
          mace_check(
              False, "The pack's pb_type is not supported: %s" % pb_type
          )
  
imports: from google.protobuf.descriptor import FieldDescriptor
  from utils.util import mace_check
  import sys
  import struct
  import tempfile
label_desc: Use image node_id 4 for calling the ProtoConverter obj's underlying member method code with example usage: obj.pack(value, pb_type) and returns: struct, struct, struct, struct, struct, struct, struct, bytes