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+#!/bin/env slides
+
+# Purple - what is it?
+
+![](purple-boys.jpg)
+
+```demo
+sxiv -sf purple-boys.jpg
+```
+
+---
+
+# Retinal Cones
+
+Purple is a mix of red and blue light.
+
+![](retinal_cones.png)
+
+```demo
+sxiv -sf retinal_cones.png
+```
+
+Our eyes see it as violet.
+
+---
+
+```demo
+printf '\033[2J'
+python3 purple.py
+read -p "Press enter to continue"
+```
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