I'm trying to use variable 'b' in re.findall with operators '\w+' but get syntax error

THIS DOESN'T WORK

import re
a = '>text<'
b = '>'
d = re.findall (r b\w+, a)
print (d)

BUT THIS IS WORKING:

import re
a = '>text<'
b = '>'
d = re.findall (r '>\w+', a)
print (d)