<!DOCTYPE html>
<html lang="en-US">
<head>
<style>
rect{
fill: url(#rainbow);
}
</style>
</head>
<body>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 600 300">
<defs>
<linearGradient id="rainbow" gradientUnits="userSpaceOnUse" x1="0" y1="0" x2="100%" y2="0">
<stop offset="0" stop-color="#ff0000"></stop>
<stop offset="0.3" stop-color="#ffff00"></stop>
<stop offset="0.6" stop-color="#00ff00"></stop>
<stop offset="0.9" stop-color="#800080"></stop>
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<g font-weight="bold">
<text x="0" y="5%">Default</text>
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<text x="0" y="26%">Identity</text>
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<text x="0" y="47%">Table lookup</text>
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<text x="0" y="68%">Linear function</text>
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<text x="0" y="89%">Gamma function</text>
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</g>
</svg>
</body>
</html>