hamburger menu
Codrops article:
http://tympanus.net/codrops/2015/11/12/animating-svg-menu-icon-segment/
VisualHierarchy article:
https://visualhierarchy.co/blog/improve-your-ux-functional-animations/
DigitalSynopsis article:
http://digitalsynopsis.com/design/gif-icons-menu-transition-animations/