Python: most idiomatic way to convert None to empty string?

Question

What is the most idiomatic way to do the following?

def xstr(s):
    if s is None:
        return \'\'
    else:
        return s

s = xstr(a) + xstr(b)
         


        

Answer 1

A neat one-liner to do this building on some of the other answers:

s = (lambda v: v or '')(a) + (lambda v: v or '')(b)

or even just:

s = (a or '') + (b or '')