def validSignup():
    dialog = MDDialog(
        title="You have successfully signed up",
        text="You can go back to the log in page to start using the app")
    dialog.width = "250"
    dialog.open()
def invalidSignup():
    dialog = MDDialog(title="Invalid  email or password",
                      text="The password has to contain at least 6 characters")
    dialog.width = "250"
    dialog.open()
def invalidLogin():
    dialog = MDDialog(title="Invalid e-mail or password",
                      text="Please try again")
    dialog.width = "250"
    dialog.open()