Trying to use python-3.5

.travis.yml

@@ -7,6 +7,9 @@ env:
   - C_COMPILER=gcc-5 CXX_COMPILER=g++-5
   - C_COMPILER=clang-3.8 CXX_COMPILER=clang++-3.8
 
+python:
+  - "3.5"
+
 before_install:
   - sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
   - wget -O - http://llvm.org/apt/llvm-snapshot.gpg.key | sudo apt-key add -