Regex: Remove all match plus one char before all

[wavic]

I have to learn regular expressions at last 

>>> import re
>>> s = 'it BS|BS||BS||BS||BS||BS|this is o n  |BS||BS||BS||BS||BS|an example'
>>> new_s = s.replace('|BS|', '\b')
>>> new_s
'it BS\x08\x08\x08\x08\x08this is o n  \x08\x08\x08\x08\x08an example'
>>> while '\x08' in new_s:
...     new_s = re.sub('[^\x08]\x08', '', new_s)
...     
>>> new_s
'this is an example'
>>> 

Thanks to this