If you're running code from this site in a Google Colab environment you may run into problems with the LaTeX content. Following the advice of Dhirendra, a working LaTeX environment can be set up with the following commands:
! sudo apt-get install texlive-latex-recommended
! sudo apt-get install dvipng texlive-latex-extra texlive-fonts-recommended
! wget http://mirrors.ctan.org/macros/latex/contrib/type1cm.zip
! unzip type1cm.zip -d /tmp/type1cm
! cd /tmp/type1cm/type1cm/ && sudo latex type1cm.ins
! sudo mkdir /usr/share/texmf/tex/latex/type1cm
! sudo cp /tmp/type1cm/type1cm/type1cm.sty /usr/share/texmf/tex/latex/type1cm
! sudo texhash
! apt install cm-super