"><span class="identifier">on_success</span></code> handlers
        are callback hooks to client code that are executed by the parser after a
        <span class="emphasis"><em>successful</em></span> parse, <code class="computeroutput"><span class="identifier">on_error</span></code>
        handlers are callback hooks to client code that are executed by the parser
        when an <code class="computeroutput"><span class="identifier">expectation_failure</span></code>
        is thrown via the expect operato