Generate Plot of chapters from Ao3 work ID

import requests
from bs4 import BeautifulSoup
from datetime import datetime
import matplotlib.pyplot as plt
import numpy as np
import sys

# Read the work id from the arguments
work_id = sys.argv[1]

# Stick the work id into the rest of the link
link = f'https://archiveofourown.org/works/{work_id}/navigate'

# Download the webpage and keep it around as html text
html_text = requests.get(link).text;

# Parse the html text into whatever tree thing BS uses
soup = BeautifulSoup(html_text, 'html.parser')

# Search the tree for all the datetime spans
spans = soup.find_all('span', {'class': 'datetime'})

# Grab the story title and author name
info = soup.find_all('h2', {'class': 'heading'})[0]
title, author = [v.text for v in info.find_all('a')]

# Convert a list of spans to a list of datetime objects
dates = [datetime.strptime(date.text, '(%Y-%m-%d)') for date in spans]

# Codegolf version
#dates = list(map(lambda d: datetime.strptime(d.text, '(%Y-%m-%d)'), BeautifulSoup(requests.get(link).text, 'html.parser').find_all('span', {'class': 'datetime'})))

days = []
for i in range(len(dates)-1):
    delta = (dates[i+1] - dates[i]).days
    days.append(delta)

ax = plt.figure().gca()
ax.yaxis.get_major_locator().set_params(integer=True)

plt.title(f'Intervals for {title} by {author}')
plt.xlabel('Chapters')

coef = np.polyfit(range(0,len(days)), days, 1)
poly1d_fn = np.poly1d(coef)
plt.plot(days, 'k.', poly1d_fn(range(0,len(days))), '--k')
plt.show()