python - How to check that the two consecutive words have the same regex pattern -

i've tried several hours couldn't reach goal.

here string:'hello world, way stackoverflow cool place'. i'm looking match 2 consecutive words have same regex pattern.

for example want replace words consecutive , start capital letter string "xx".

so when applied string result should be:

hello world,xx xx xx stackoverflow cool place

here snippet:

mystring='hello world,by way stackoverflow cool place' re.sub(r"[a-z]\w+","xx",mystring) 

but i'm getting is: 'xx world,xx xx xx stackoverflow cool place'

using regex module:

>>> import regex >>> text = 'hello world,by way stackoverflow cool place' >>> regex.sub(r'\b[a-z]\w+(?=\s+[a-z]\w+)|(?<=\b[a-z]\w+\s+)[a-z]\w+', 'xx', text) 'hello world,xx xx xx stackoverflow cool place'