Convert MathML back into Math-Tex, but with only a subset of MathML syntaxes is supported (yet extending it is quite simple).
Run on Python 2.7, may run on Python 3.x too.
BeautifulSoup 4. To install it, just run
pip install bs4
from mathml2tex import MathMLTeX
m = MathMLTeX()
xml = '''<math xmlns="https://www.w3.org/1998/Math/MathML">
<msqrt>
<mn>2</mn>
</msqrt>
</math>'''
m.convert(xml) # -> '\\sqrt{2}'