code: private function isEqualPartOfDeclareStatement(Tokens $tokens, $index)
      {
          $prevMeaningfulIndex = $tokens->getPrevMeaningfulToken($index);
          if ($tokens[$prevMeaningfulIndex]->isGivenKind(T_STRING)) {
              $prevMeaningfulIndex = $tokens->getPrevMeaningfulToken($prevMeaningfulIndex);
              if ($tokens[$prevMeaningfulIndex]->equals('(')) {
                  $prevMeaningfulIndex = $tokens->getPrevMeaningfulToken($prevMeaningfulIndex);
                  if ($tokens[$prevMeaningfulIndex]->isGivenKind(T_DECLARE)) {
                      return $prevMeaningfulIndex;
                  }
              }
          }
  
          return false;
      }
docs: @param Tokens $tokens
  @param int    $index
  
  @return false|int index of T_DECLARE where the `=` belongs to or `false`