1. enable activity recognition in your android for step walked demo
2. firebase core and firestore package for data storing(collection reference ) CollectionReference collRef = FirebaseFirestore.instance.collection('user_info'); we use collRef to store document inside collection.
3. DocumentReference docRef = FirebaseFirestore.instance for fetching data from document
4. StreamBuilder we use this to see change in firestore data n real time changes okay docSnapshot.data() give==> { 'name': 'Shrijana', 'age': 21, 'phone': '98634648' }
5. basically, the future builder wdget is used whenever we want to fetch a data from outside that may be late or null or async, to handle such things ?null huna sakxa, !. null hudaina fix