Take a look at the example of the python interface's administrative address book.

Add "person" means to add a person to the address book and enter personal information.

List > people list the people who are already in the address book.

First define your own addressbook.proto

syntax = "proto3";
package tutorial;
message Person {
  required string name = 1;
  required int32 id = 2;
  optional string email = 3;

  enum PhoneType {
    MOBILE = 0;
    HOME = 1;
    WORK = 2;
  }

  message PhoneNumber {
    required string number = 1;
    optional PhoneType type = 2 [default = HOME];
  }

  repeated PhoneNumber phones = 4;
}

message AddressBook {
  repeated Person people = 1;
}

Then compile the proto file

protoc -I=$SRC_DIR --python_out=$DST_DIR $SRC_DIR/addressbook.proto

SRC dir is the path to be compiled at present, DST dir is the path of python script to be compiled and output.

Then write a Message's add_person.py

#! /usr/bin/env python
import addressbook_pb2
import sys

# This function fills in a Person message based on user input.
def PromptForAddress(person):
  person.id = int(raw_input("Enter person ID number: "))
  person.name = raw_input("Enter name: ")

  email = raw_input("Enter email address (blank for none): ")
  if email != "":
    person.email = email

  while True:
    number = raw_input("Enter a phone number (or leave blank to finish): ")
    if number == "":
      break

    phone_number = person.phones.add()
    phone_number.number = number

    type = raw_input("Is this a mobile, home, or work phone? ")
    if type == "mobile":
      phone_number.type = addressbook_pb2.Person.MOBILE
    elif type == "home":
      phone_number.type = addressbook_pb2.Person.HOME
    elif type == "work":
      phone_number.type = addressbook_pb2.Person.WORK
    else:
      print "Unknown phone type; leaving as default value."

# Main procedure:  Reads the entire address book from a file,
#   adds one person based on user input, then writes it back out to the same
#   file.
if len(sys.argv) != 2:
  print "Usage:", sys.argv[0], "ADDRESS_BOOK_FILE"
  sys.exit(-1)

address_book = addressbook_pb2.AddressBook()

# Read the existing address book.
try:
  with open(sys.argv[1], "rb") as f:
    address_book.ParseFromString(f.read())
except IOError:
  print sys.argv[1] + ": File not found.  Creating a new file."

# Add an address.
PromptForAddress(address_book.people.add())

# Write the new address book back to disk.
with open(sys.argv[1], "wb") as f:
  f.write(address_book.SerializeToString())

Finally, read a Message script list_people.py

#! /usr/bin/env python
import addressbook_pb2
import sys

# Iterates though all people in the AddressBook and prints info about them.
def ListPeople(address_book):
  for person in address_book.people:
    print "Person ID:", person.id
    print "  Name:", person.name
    if person.email != "":
      print "  E-mail address:", person.email

    for phone_number in person.phones:
      if phone_number.type == addressbook_pb2.Person.MOBILE:
        print "  Mobile phone #:",
      elif phone_number.type == addressbook_pb2.Person.HOME:
        print "  Home phone #:",
      elif phone_number.type == addressbook_pb2.Person.WORK:
        print "  Work phone #:",
      print phone_number.number

# Main procedure:  Reads the entire address book from a file and prints all
#   the information inside.
if len(sys.argv) != 2:
  print "Usage:", sys.argv[0], "ADDRESS_BOOK_FILE"
  sys.exit(-1)

address_book = addressbook_pb2.AddressBook()

# Read the existing address book.
with open(sys.argv[1], "rb") as f:
  address_book.ParseFromString(f.read())

ListPeople(address_book)

In fact, the same way as Protocol Buffers2 is only a small change.