How to use the secp256k1.lib.secp256k1_context_create function in secp256k1

# -*- coding: utf-8 -*-
from __future__ import print_function

import contextlib
import timeit

import secp256k1

from raiden.utils import sha3, privatekey_to_address
from raiden.messages import decode
from raiden.messages import (
    Ack, ConfirmTransfer, DirectTransfer, Lock, MediatedTransfer, Ping,
    RefundTransfer, Secret, SecretRequest, TransferTimeout,
)

GLOBAL_CTX = secp256k1.lib.secp256k1_context_create(secp256k1.ALL_FLAGS)

PRIVKEY_BIN = 'x' * 32
PRIVKEY = secp256k1.PrivateKey(PRIVKEY_BIN, ctx=GLOBAL_CTX, raw=True)
ADDRESS = privatekey_to_address(PRIVKEY_BIN)
HASH = sha3(PRIVKEY)
ITERATIONS = 1000000  # timeit default


def run_timeit(message_name, message, iterations=ITERATIONS):
    data = message.encode()

    def test_encode():
        message.encode()

    def test_decode():
        decode(data)

#!/usr/bin/python
from .py2specials import *
from .py3specials import *
import binascii
import hashlib
import re
import sys
import os
import base64
import time
import random
import hmac
import secp256k1

#Global context for secp256k1 operations (helps with performance)
ctx = secp256k1.lib.secp256k1_context_create(secp256k1.ALL_FLAGS)

#Standard prefix for Bitcoin message signing.
BITCOIN_MESSAGE_MAGIC = '\x18' + 'Bitcoin Signed Message:\n'

"""A custom nonce function acting as a pass-through.
Only used for reusable donation pubkeys (stealth).
"""
from cffi import FFI

ffi = FFI()
ffi.cdef('static int nonce_function_rand(unsigned char *nonce32,'
         'const unsigned char *msg32,const unsigned char *key32,'
         'const unsigned char *algo16,void *data,unsigned int attempt);')

ffi.set_source("_noncefunc",
"""

#!/usr/bin/python
from .py2specials import *
from .py3specials import *
import binascii
import hashlib
import re
import sys
import os
import base64
import time
import random
import hmac
import secp256k1

ctx = secp256k1.lib.secp256k1_context_create(secp256k1.ALL_FLAGS)

def privkey_to_address(priv, from_hex=True, magicbyte=0):
    return pubkey_to_address(privkey_to_pubkey(priv, from_hex), magicbyte)

privtoaddr = privkey_to_address

# Hashes
def bin_hash160(string):
    intermed = hashlib.sha256(string).digest()
    return hashlib.new('ripemd160', intermed).digest()

def hash160(string):
    return safe_hexlify(bin_hash160(string))

def bin_sha256(string):
    binary_data = string if isinstance(string, bytes) else bytes(string,