the error message that is later used whenever the parser is applied and doesn’t find <code
      class="fsharp"><span class="ci">str</span></code> in the input (we’ll write more about error messages in later chapters).
     </p>
    </div>
    <div class="para _6">
     <p>
      The actual parsing logic is completely straightforward: On <span class="i">line 5</span> the parser calls the CharStream’s <code
      class="fsharp"><a href="../reference/charstream.html#CharStream.members.Skip"><span class=