Add python 3.4 and 3.3 versions support

.travis.yml

@@ -1,16 +1,63 @@
 language: python
-python:
-- '2.7'
-- '3.5'
-- '3.6'
-- '3.7'
-- '3.8'
 cache: pip
-install:
-- pip install flake8
-script:
-- flake8 --count
-- python setup.py bdist_wheel
+jobs:
+  include:
+    - name: "Python 3.8"
+      dist: xenial
+      python: '3.8'
+      install:
+        - pip install -r requirements.txt
+      script:
+        - flake8 --count
+        - python setup.py bdist_wheel
+    - name: "Python 3.7"
+      dist: xenial
+      python: '3.7'
+      install:
+        - pip install -r requirements.txt
+      script:
+        - flake8 --count
+        - python setup.py bdist_wheel
+    - name: "Python 3.6"
+      dist: xenial
+      python: '3.6'
+      install:
+        - pip install -r requirements.txt
+      script:
+        - flake8 --count
+        - python setup.py bdist_wheel
+    - name: "Python 3.5"
+      dist: xenial
+      python: '3.5'
+      install:
+        - pip install -r requirements.txt
+        - flake8 --count
+      script:
+        - python setup.py bdist_wheel
+    - name: "Python 3.4"
+      dist: trusty
+      python: '3.4'
+      install:
+        - pip install -I -r requirements.txt
+      script:
+        - flake8 --count --ignore=F401 .
+        - python setup.py bdist_wheel
+    - name: "Python 3.3"
+      dist: trusty
+      python: '3.3'
+      install:
+        - pip install -I -r requirements.txt
+      script:
+        - flake8 --count --ignore=F401 .
+        - python setup.py bdist_wheel
+    - name: "Python 2.7"
+      dist: xenial
+      python: '2.7'
+      install:
+        - pip install -r requirements.txt
+      script:
+        - flake8 --count
+        - python setup.py bdist_wheel
 before_deploy: python setup.py sdist
 deploy:
   - provider: pypi

requirements.txt

@@ -1,2 +1,11 @@
-setuptools
-typing;python_version<"3.5"
+flake8>=3.8;python_version>="3.5"
+setuptools>=49.6;python_version>="3.5"
+flake8>=2.6,<3.0;python_version=='3.4'
+flake8>=2.6,<3.0;python_version=='3.3'
+setuptools==39.2 ;python_version=='3.4'
+setuptools==39.2 ;python_version=='3.3'
+typing>=3.6,<3.7;python_version=='3.4'
+typing>=3.6,<3.7;python_version=='3.3'
+flake8>=3.8;python_version<'3'
+setuptools>=44.1;python_version<"3"
+typing>=3.7;python_version<"3"

setup.py

@@ -24,6 +24,8 @@
         "Programming Language :: Python :: 2",
         "Programming Language :: Python :: 2.7",
         "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.3",
+        "Programming Language :: Python :: 3.4",
         "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",