Correct flake8 errors

Remove unused imports
Make regexp strings raw strings in bip21 and amount.py
Remove copy of classmethod in wallet.py

jmbitcoin/jmbitcoin/amount.py

@@ -21,7 +21,7 @@ def sat_to_btc(sat):
 
 def amount_to_sat(amount_str):
     amount_str = str(amount_str).strip()
-    if re.compile("^[0-9]{1,8}(\.)?([0-9]{1,8})?(btc|sat)?$").match(
+    if re.compile(r"^[0-9]{1,8}(\.)?([0-9]{1,8})?(btc|sat)?$").match(
                   amount_str.lower()) is None:
         raise ValueError("Invalid BTC amount string " + amount_str)
     if amount_str.lower().endswith("btc"):

jmbitcoin/jmbitcoin/bip21.py

@@ -15,7 +15,7 @@ def is_bip21_uri(uri):
 
 
 def is_bip21_amount_str(amount):
-    return re.compile("^[0-9]{1,8}(\.[0-9]{1,8})?$").match(str(amount)) != None
+    return re.compile(r"^[0-9]{1,8}(\.[0-9]{1,8})?$").match(str(amount)) != None
 
 
 def validate_bip21_amount(amount):

jmclient/jmclient/taker_utils.py

@@ -5,7 +5,6 @@ import os
 import sys
 import time
 import numbers
-from binascii import hexlify
 
 from jmbase import get_log, jmprint
 from .configure import jm_single, validate_address, is_burn_destination

jmclient/jmclient/wallet.py

@@ -1706,12 +1706,6 @@ class FidelityBondMixin(object):
     def is_timelocked_path(cls, path):
         return len(path) > 4 and path[4] == cls.BIP32_TIMELOCK_ID
 
-    def get_xpub_from_fidelity_bond_master_pub_key(cls, mpk):
-        if mpk.startswith(cls._BIP32_PUBKEY_PREFIX):
-            return mpk[len(cls._BIP32_PUBKEY_PREFIX):]
-        else:
-            return False
-
     def _get_key_ident(self):
         first_path = self.get_path(0, 0)
         priv, engine = self._get_key_from_path(first_path)

jmclient/jmclient/wallet_service.py

@@ -5,7 +5,6 @@ import time
 import ast
 import binascii
 import sys
-import itertools
 from decimal import Decimal
 from copy import deepcopy
 from twisted.internet import reactor