selenium-twitter-login.py

from selenium import webdriver
from getpass import getpass

def login_twitter(username, password):
    driver = webdriver.Firefox()
    driver.get("https://twitter.com/login")

    username_field = driver.find_element_by_class_name("js-username-field")
    password_field = driver.find_element_by_class_name("js-password-field")

    username_field.send_keys(username)
    driver.implicitly_wait(1)
    
    password_field.send_keys(password)
    driver.implicitly_wait(1)

    driver.find_element_by_class_name("EdgeButtom--medium").click()


if __name__ == "__main__":
    username = input("user name : ")
    password = getpass("password  : ")
    login_twitter(username, password)

not working

error:
NoSuchElementException: Message: Unable to locate element: .js-username-field

Because twitter is updated. You can use that code to select correct user input
driver.findElement(By.name("session[username_or_email]"))
driver.findElement(By.name("session[password]"))

Actually in Python it should be

driver.find_element_by_name("session[username_or_email]")
driver.find_element_by_name("session[password]")

how to find login button?

You don't need the login button, instead you could submit after entering the password, like this

        ...
        password_field.send_keys(password)
        driver.implicitly_wait(1)
        password_field.submit()

how to find login button?

Actually you can send newline character "\n" after your password.
for example:
username: "username"
password: "password\n"