title: how to verify email and password flutter firebase
body: <p>i'm new with flutter and i want to implement a log in screen on my application.
  for that i use flutter and firebase.
  the problem is that when anything in the email and password field the application access to the home.
  so i need to verify the email before get the access.</p>
  <p>here is the code</p>
  <p>thanks guys for help me,</p>
  <pre><code>               onPressed: () {
                  if (_formKey.currentState.validate()) {
                    Future&lt;String&gt; check = logIn();
                    if (check != null) {
                      Navigator.pushReplacement(
                          context,
                          MaterialPageRoute(
                              builder: (BuildContext context) =&gt;
                                  HomePage()));
                    }
                  }
                
  </code></pre>