Update binary_search_tree.py (#1339)

* Update binary_search_tree.py

remove some bugs

* Update binary_search_tree.py

* Update binary_search_tree.py

* Update binary_search_tree.py

* Update binary_search_tree.py

* Update binary_search_tree.py

* Update binary_search_tree.py

* testlist = (8, 3, 6, 1, 10, 14, 13, 4, 7)

* Update .travis.yml

Co-authored-by: Christian Clauss <cclauss@me.com>

Author: Hocnonsense

.travis.yml

@@ -6,6 +6,7 @@ install: pip install -r requirements.txt
 before_script:
   - black --check . || true
   - flake8 . --count --select=E101,E9,F4,F63,F7,F82,W191 --show-source --statistics
+  - flake8 . --count --exit-zero --max-line-length=127 --statistics
 script:
   - scripts/validate_filenames.py  # no uppercase, no spaces, in a directory
   - mypy --ignore-missing-imports .