code: private function getGroupDeclaration(Tokens $tokens, $index)
      {
          $groupPrefix = '';
          $comment = '';
          for ($i = $index + 1;; ++$i) {
              if ($tokens[$i]->isGivenKind(CT::T_GROUP_IMPORT_BRACE_OPEN)) {
                  $groupOpenIndex = $i;
  
                  break;
              }
  
              if ($tokens[$i]->isComment()) {
                  $comment .= $tokens[$i]->getContent();
                  if (!$tokens[$i - 1]->isWhitespace() && !$tokens[$i + 1]->isWhitespace()) {
                      $groupPrefix .= ' ';
                  }
  
                  continue;
              }
  
              if ($tokens[$i]->isWhitespace()) {
                  $groupPrefix .= ' ';
  
                  continue;
              }
  
              $groupPrefix .= $tokens[$i]->getContent();
          }
  
          return [
              rtrim($groupPrefix),
              $groupOpenIndex,
              $tokens->findBlockEnd(Tokens::BLOCK_TYPE_GROUP_IMPORT_BRACE, $groupOpenIndex),
              $comment,
          ];
      }
docs: @param Tokens $tokens
  @param int    $index
  
  @return array