title: Split list into list of lists with a list as a parameter for where to split OCaml
body: <p>I am new to OCaml and curious as to how to write a function called <code>Seperate_by</code> that takes in two parameters, a list and a list of elements on where to split the original list.</p>
  <p>For example,</p>
  <pre><code>Seperate_by [1;2;3;4;5;6;7] [3;5]
  </code></pre>
  <p>Should have an output of <code>[[1;2];[4];[6;7]] </code>.</p>