tests: Use explicit imports

test/functional/feature_cltv.py

@@ -8,11 +8,13 @@ Test that the CHECKLOCKTIMEVERIFY soft-fork activates at (regtest) block height
 1351.
 """
 
-from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import *
-from test_framework.mininode import *
 from test_framework.blocktools import create_coinbase, create_block, create_transaction
+from test_framework.messages import CTransaction, msg_block, ToHex
+from test_framework.mininode import mininode_lock, P2PInterface
 from test_framework.script import CScript, OP_1NEGATE, OP_CHECKLOCKTIMEVERIFY, OP_DROP, CScriptNum
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal, bytes_to_hex_str, hex_str_to_bytes, wait_until
+
 from io import BytesIO
 
 CLTV_HEIGHT = 1351