code: private function normalizeUri(string $base, string $uri) : string
      {
          $full = $base . $uri;
  
          if (empty($full)) {
              return '';
          }
  
          $full = preg_replace('#/+#', '/', $full);
  
          return $full[0] === '/' ? $full : '/' . $full;
      }
docs: @param string $base
  @param string $uri
  
  @return string