pen-and-half-close-interval"><i class="fa fa-check"></i><b>1.2.3</b> Half Open and Half Close Interval</a></li>
<li class="chapter" data-level="1.2.4" data-path="notations-and-functions.html"><a href="notations-and-functions.html#graph"><i class="fa fa-check"></i><b>1.2.4</b> Graph</a></li>
</ul></li>
<li class="chapter" data-level="1.3" data-path="notations-and-functions.html"><a href="notations-and-functions.html#what-is-a-function"><i class="fa fa-check"></i><b>1.3</b> What is a Function?</a></li>
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