original_string: protected function getPrepareCorsHeaders($headers)
      {
          if (array_key_exists(CorsResponseHeaders::EXPOSE_HEADERS, $headers) === true) {
              $headers[CorsResponseHeaders::EXPOSE_HEADERS] =
                  implode(', ', $headers[CorsResponseHeaders::EXPOSE_HEADERS]);
          }
  
          return $headers;
      }
code: protected function getPrepareCorsHeaders($headers)
      {
          if (array_key_exists(CorsResponseHeaders::EXPOSE_HEADERS, $headers) === true) {
              $headers[CorsResponseHeaders::EXPOSE_HEADERS] =
                  implode(', ', $headers[CorsResponseHeaders::EXPOSE_HEADERS]);
          }
  
          return $headers;
      }
code_tokens: protected function getPrepareCorsHeaders ( $ headers ) { if ( array_key_exists ( CorsResponseHeaders :: EXPOSE_HEADERS , $ headers ) === true ) { $ headers [ CorsResponseHeaders :: EXPOSE_HEADERS ] = implode ( ', ' , $ headers [ CorsResponseHeaders :: EXPOSE_HEADERS ] ) ; } return $ headers ; }
docstring: There is an issue with IE which cannot work with multiple 'Access-Control-Expose-Headers' and
  requires it them to be comma separated. Chrome and Firefox seem to be not affected.
  
  @param array $headers
  
  @return array
  
  @see https://github.com/neomerx/cors-psr7/issues/31
docstring_tokens: There is an issue with IE which cannot work with multiple Access - Control - Expose - Headers and requires it them to be comma separated . Chrome and Firefox seem to be not affected .