Error message "error: command 'gcc' failed with exit status 1" while installing eventlet

I wanted to install [Eventlet][1] on my system in order to have "Herd" for software deployment, but the terminal is showing a GCC error (as root): ```lang-none cd ~ easy_install -U eventlet ``` Output: ```lang-none Searching for eventlet Reading http://pypi.python.org/simple/eventlet/ Reading http://wiki.secondlife.com/wiki/Eventlet Reading http://eventlet.net Best match: eventlet 0.9.16 Processing eventlet-0.9.16-py2.7.egg eventlet 0.9.16 is already the active version in easy-install.pth Using /usr/local/lib/python2.7/dist-packages/eventlet-0.9.16-py2.7.egg Processing dependencies for eventlet Searching for greenlet>=0.3 Reading http://pypi.python.org/simple/greenlet/ Reading https://github.com/python-greenlet/greenlet Reading http://bitbucket.org/ambroff/greenlet Best match: greenlet 0.3.4 Downloading http://pypi.python.org/packages/source/g/greenlet/greenlet- 0.3.4.zip#md5=530a69acebbb0d66eb5abd83523d8272 Processing greenlet-0.3.4.zip Writing /tmp/easy_install-_aeHYm/greenlet-0.3.4/setup.cfg Running greenlet-0.3.4/setup.py -q bdist_egg --dist-dir /tmp/easy_install-_aeHYm/greenlet-0.3.4/egg-dist-tmp-t9_gbW In file included from greenlet.c:5:0: greenlet.h:8:20: fatal error: Python.h: No such file or directory compilation terminated. error: Setup script exited with error: command 'gcc' failed with exit status 1` ``` Why can't *Python.h* be found? [1]: https://eventlet.readthedocs.io/en/latest/