input = '''
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1 1">
<pattern id="patt1" patternUnits="userSpaceOnUse" width="20" height="40"/>
<rect fill="url(#patt1)" width="10" height="10"/>
</svg>
'''
output = '''
<svg
xmlns="http://www.w3.org/2000/svg"
width="1"
height="1"
viewBox="0 0 1 1"
preserveAspectRatio="xMidYMid"
xmlns:usvg="https://github.com/RazrFalcon/usvg"
usvg:version="0.4.0">
<defs/>
</svg>
'''