Hello. I'm really not sure about the defined re pattern for this exercise, especially how to define the string words between == on both sides in order to remove it as a whole header. Could you please provide me with any tips if you happen to know that. Thank you! 
My exercise:
Wikipedia uses two or more equal signs == to mark headers and subheaders in the articles (e.g. ==, ===, ====).
In all cases, the equal signs and the actual header text are separated by spaces on both sides, e.g. == History == or === Further reading ===.
Import the re module and define a regular expression that removes all headers and subheaders from the articles. Store this regular expression under a variable named pattern.
Apply the regular expression under pattern to each article (string object) in the list wiki_articles. Store each processed article into a new list named cleaned_articles.
My answer:
My exercise:
Wikipedia uses two or more equal signs == to mark headers and subheaders in the articles (e.g. ==, ===, ====).
In all cases, the equal signs and the actual header text are separated by spaces on both sides, e.g. == History == or === Further reading ===.
Import the re module and define a regular expression that removes all headers and subheaders from the articles. Store this regular expression under a variable named pattern.
Apply the regular expression under pattern to each article (string object) in the list wiki_articles. Store each processed article into a new list named cleaned_articles.
My answer:
import re
cleaned_articles=[]
for string_object in wiki_articles:
pattern = re.compile(r'={2,}.+') #not sure about the defined pattern
processed = pattern.sub(repl='', string=string_object)
cleaned_articles.append(processed)