doc: test: suggest multi-line imports in functional test style guide

test/functional/README.md

@@ -28,7 +28,9 @@ don't have test cases for.
   could lead to bugs and issues in the test code.
 - Use [type hints](https://docs.python.org/3/library/typing.html) in your code to improve code readability
   and to detect possible bugs earlier.
-- Avoid wildcard imports
+- Avoid wildcard imports.
+- If more than one name from a module is needed, use lexicographically sorted multi-line imports
+  in order to reduce the possibility of potential merge conflicts.
 - Use a module-level docstring to describe what the test is testing, and how it
   is testing it.
 - When subclassing the BitcoinTestFramework, place overrides for the

test/functional/example_test.py

@@ -14,8 +14,15 @@ is testing and *how* it's being tested
 from collections import defaultdict
 
 # Avoid wildcard * imports
-from test_framework.blocktools import (create_block, create_coinbase)
-from test_framework.messages import CInv, MSG_BLOCK
+# Use lexicographically sorted multi-line imports
+from test_framework.blocktools import (
+    create_block,
+    create_coinbase,
+)
+from test_framework.messages import (
+    CInv,
+    MSG_BLOCK,
+)
 from test_framework.p2p import (
     P2PInterface,
     msg_block,