mino-acids" id="toc-amino-acids" class="nav-link active" data-scroll-target="#amino-acids">Amino Acids</a></li>
  <li><a href="#mass-dict" id="toc-mass-dict" class="nav-link" data-scroll-target="#mass-dict">Mass dict</a>
  <ul>
  <li><a href="#get_mass_dict" id="toc-get_mass_dict" class="nav-link" data-scroll-target="#get_mass_dict">get_mass_dict</a></li>
  </ul></li>
  <li><a href="#isotopes" id="toc-isotopes" class="nav-link" data-scroll-target="#isotopes">Isotopes</a>
  <ul>
  <li><a href="#isotope" id="