Add mandelbrot snippet

wasm/demo/snippets/mandelbrot.py

@@ -0,0 +1,31 @@
+# NOTE: will take a while, up to around a minute, to run.
+# Expect this page to freeze.
+
+w = 50.0
+h = 50.0
+
+y = 0.0
+while y < h:
+    x = 0.0
+    while x < w:
+        Zr, Zi, Tr, Ti = 0.0, 0.0, 0.0, 0.0
+        Cr = 2 * x / w - 1.5
+        Ci = 2 * y / h - 1.0
+
+        i = 0
+        while i < 50 and Tr + Ti <= 4:
+            Zi = 2 * Zr * Zi + Ci
+            Zr = Tr - Ti + Cr
+            Tr = Zr * Zr
+            Ti = Zi * Zi
+            i = i + 1
+
+        if Tr + Ti <= 4:
+            print('*', end='')
+        else:
+            print('·', end='')
+
+        x = x + 1
+
+    print()
+    y = y + 1