human
Regex. Match words that contain special characters or 'http://'
assistant
Here is some code to replace each occurrence of the pattern '(http://\\S+|\\S*[^\\w\\s]\\S*)' within `a` with ''

re.sub('(http://\\S+|\\S*[^\\w\\s]\\S*)', '', a)

#Warning: this code generation is experimental. Please inspect the code for any bugs before executing.