message: [tests] Add docstring for wallet_importmulti.py
  Adds a docstring describing the new importmulti test.
diff: # Copyright (c) 2014-2018 The Bitcoin Core developers
  # Distributed under the MIT software license, see the accompanying
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  -"""Test the importmulti RPC."""
  +"""Test the importmulti RPC.
  +
  +Test importmulti by generating keys on node0, importing the scriptPubKeys and
  +addresses on node1 and then testing the address info for the different address
  +variants.
  +
  +- `get_key()` and `get_multisig()` are called to generate keys on node0 and
  + return the privkeys, pubkeys and all variants of scriptPubKey and address.
  +- `test_importmulti()` is called to send an importmulti call to node1, test
  + success, and (if unsuccessful) test the error code and error message returned.
  +- `test_address()` is called to call getaddressinfo for an address on node1
  + and test the values returned."""
  from collections import namedtuple
  from test_framework.address import (
  