anchor.diff:                      widget.user.providerData.isEmpty
                           ? 'No providers'
                           : 'Providers:',
  -                    style: TextStyle(fontWeight: FontWeight.bold),
  +                    style: const TextStyle(fontWeight: FontWeight.bold),
                       textAlign: TextAlign.center,
                     ),
                     for (var provider in widget.user.providerData)
                       Dismissible(
                         key: Key(provider.uid),
  +                      onDismissed: (action) =>
  +                          widget.user.unlink(provider.providerId),
                         child: Card(
                           color: Colors.grey[700],
                           child: ListTile(
  
positive.code:   Widget build(BuildContext context) {
      return Card(
        child: Padding(
          padding: const EdgeInsets.all(16.0),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Container(
                child: const Text(
                  "User info",
                  style: TextStyle(fontWeight: FontWeight.bold),
                ),
                padding: EdgeInsets.only(bottom: 8.0),
                alignment: Alignment.center,
              ),
              if (widget.user != null)
                if (widget.user.photoURL != null)
                  Container(
                    child: Image.network(widget.user.photoURL),
                    alignment: Alignment.center,
                    margin: EdgeInsets.only(bottom: 8.0),
                  )
                else
                  Align(
                    alignment: Alignment.center,
                    child: Container(
                      child: Text(
                        "No image",
                        textAlign: TextAlign.center,
                      ),
                      padding: EdgeInsets.all(8.0),
                      margin: EdgeInsets.only(bottom: 8.0),
                      color: Colors.black,
                    ),
                  ),
              Text(widget.user == null
  
negative.code:                 photoURL: _urlController.text);
              Navigator.of(context).pop();
            },
            child: const Text('Update'),
          )
        ],
      );
  