### How to install dlib v19.9 or newer (w/ python bindings) from github on macOS and Ubuntu

Pre-reqs:
- Have Python 3 installed. On macOS, this could be installed from homebrew or even via standard 
  Python 3.6 downloaded installer from https://www.python.org/download. On Linux, just use your
  package manager.
- On macOS:
  - Install XCode from the Mac App Store (or install the XCode command line utils).
  - Have [homebrew](https://brew.sh/) installed
- On Linux:
  - For a full list of apt packages required, check out the [example Dockerfile](https://github.com/ageitgey/face_recognition/blob/master/Dockerfile#L6-L34) and copy what's installed there.
  - These instructions assume you are using Ubuntu 16.04 or newer. If you are using 14.04, you can try [these installation instructions instead](https://github.com/ageitgey/face_recognition/issues/120) to work around the old CMake version.
- These instructions assume you don't have an nVidia GPU and don't have Cuda and cuDNN installed and don't want
  GPU acceleration (since none of the current Mac models support this).

Clone the code from github:

```bash
git clone https://github.com/davisking/dlib.git
```

Build the main dlib library (optional if you just want to use Python):

```bash
cd dlib
mkdir build; cd build; cmake ..; cmake --build .
```

Build and install the Python extensions:

```bash
cd ..
python3 setup.py install
```

At this point, you should be able to run `python3` and type `import dlib` successfully.