smartest way to join two lists into a formatted string

Question

Lets say I have two lists of same length:

a = [\'a1\', \'a2\', \'a3\']
b = [\'b1\', \'b2\', \'b3\']

and I want to produce the following str

Answer 1

>>> ', '.join(i + '=' + j for i,j in zip(a,b))
'a1=b1, a2=b2, a3=b3'