beginning of the stack memory region. This is always the lower end, regardless of stack growth direction. Returns NULL if not supported by the backend. Note that some backends may only support querying user-created coroutines, but not the thread's main context.</dd></dl>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramname">co</td><td>The coroutine to query. </td></tr>
    <tr><td class="paramname">stack_size</td><td>If not NULL, the stack size is written to memor