docs: function unuse_dialect(dialectName, lexer, options) {
    options = options || {};
    if(dialectName && options.validate &&
      lexer.dialects[0].name !== dialectName)
    {
      lexer.error('Attempt to exit dialect "' + dialectName + '" while "' +
        lexer.dialects[0].name + '" was still active');
    }
  
    slinfo('removing dialect', dialectName ? ": " + dialectName : "");
    var removedDialect = lexer.pop_dialect(dialectName);
    if(!removedDialect) {
      lexer.error('The dialect ' + (dialectName ? '"' + dialectName + '"': '') +
          ' has never been used');
    }
  
  }