HTMLのスクレイピング処理で、特定の条件に合う要素を削除したり置換する方法
（＊例えば、リンクをすべてスキップしたい、図表は飛ばす、など）
Python BeautifulSoupで、.extract(), .replace_with() 関数を使う。
from bs4 import BeautifulSoup
txt = """<p>I have a dog. His name is <span class="secret">Ken</span>.</p>"""
soup = BeautifulSoup(txt)
# This keeps "unwanted" information
soup.get_text()
#: u'I have a dog. His name is Ken.'
# remove an element by tag matching
soup.find("span", {"class":"secret"}).extract()
soup.get_text()
#: u'I have a dog. His name is .'
# or you can replace that with something
soup = BeautifulSoup(txt)
soup.find("span", {"class":"secret"}).replace_with("confidential")
soup.get_text()
#: u'I have a dog. His name is confidential.'