ass="doc_error_around"><span class="doc_error_linenum">002</span><span class="doc_error_linestr"></span></li></ul><div class="doc doc_error_msg"><p class="doc_par">Error in command '<code class="doc_mono">\newtheorem</code>'. Invalid name '<code class="doc_mono">123</code>' for custom environment. A custom environment must begin with a lowercase Roman letter, and is optionally followed by lowercase Roman letters, digits, or the character '<code class="doc_mono">_</code>' (underscore).</p></div></li><li clas