(venv:/tmp/pyyam/)$ pip install pyyaml
Downloading/unpacking pyyaml
  Downloading PyYAML-3.11.tar.gz (248kB): 248kB downloaded
  Running setup.py (path:/tmp/pip-build-gjsjk9/pyyaml/setup.py) egg_info for package pyyaml
    
Installing collected packages: pyyaml
  Running setup.py install for pyyaml
    checking if libyaml is compilable
    x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fno-strict-aliasing -D_FORTIFY_SOURCE=2 -g -fstack-protector-strong -Wformat -Werror=format-security -fPIC -I/usr/include/python2.7 -c build/temp.linux-x86_64-2.7/check_libyaml.c -o build/temp.linux-x86_64-2.7/check_libyaml.o
    build/temp.linux-x86_64-2.7/check_libyaml.c:2:18: fatal error: yaml.h: No such file or directory
    compilation terminated.
    
    libyaml is not found or a compiler error: forcing --without-libyaml
    (if libyaml is installed correctly, you may need to
     specify the option --include-dirs or uncomment and
     modify the parameter include_dirs in setup.cfg)
    
Successfully installed pyyaml
Cleaning up...
$ python -c 'import yaml'; echo $?
0