import requests
from bs4 import BeautifulSoup

f = open("natu.html", "a")
natSci = "https://miupi.uprrp.edu/horarios/RBA120_CN.HTML"
page = requests.get(natSci)

soup = BeautifulSoup(page.content, 'html.parser')

f.write(soup.prettify())
f.close()