in themes/docsy/assets/js/plantuml.js [20:31]
function append3bytes(b1, b2, b3) {
c1 = b1 >> 2;
c2 = ((b1 & 0x3) << 4) | (b2 >> 4);
c3 = ((b2 & 0xF) << 2) | (b3 >> 6);
c4 = b3 & 0x3F;
r = "";
r += encode6bit(c1 & 0x3F);
r += encode6bit(c2 & 0x3F);
r += encode6bit(c3 & 0x3F);
r += encode6bit(c4 & 0x3F);
return r;
}