Swift3 iOS -Firebase FIREmailPasswordAuthProvider Not Working

I just upgraded my Firebase Cocoapods from 3.15.0 to 4.0.4 and FirebaseAuth Cocoapods from 3.1.1 to 4.0.0.

I'm using email & password to authenticate users. When a user changes their email I was using this method below and everything was working fine:

FIREmailPasswordAuthProviderID.credential(withEmail: emailTextField.text!, password: passwordTextField.text!)

Now that I updated I get the error message

Value of type 'String' has no member 'credential'

I looked on the docs and it said to use the method below:

The problem is I get the same exact error:

FIREmailAuthProviderID.credential(withEmail: emailTextField.text!, password: passwordTextField.text!)

Value of type 'String' has no member 'credential'

My original code below

import Firebase
import FirebaseAuth

let user: User?

let credential = FIREmailPasswordAuthProviderID.credential(withEmail: emailTextField.text!, password: passwordTextField.text!)

        if let user = user{
            user.reauthenticate(with: credential, completion: {
                (error) in
                if error != nil{
                    //...do something
                    return
                }
                //...do something else
            })
        }

What am I doing wrong?