I'm trying to make sure an email exist/ doesn't exist in firebase, but the method I'm trying to use does not seem to work.

This is my current code:

```
export function checkEmail(email) {
  return dispatch => {
    dispatch(checkEmailRequest());

    return window.firebase
      .auth()
      .fetchSignInMethodsForEmail(email)
      .then(results => {
        dispatch(checkEmailSuccess(results));
      })
      .catch(function(error) {
        dispatch(checkEmailFailed(error));
      });
  };
}

```

Message: TypeError: window.firebase.auth(...).fetchSignInMethodsForEmail is not a function