By reading RSA algorithm，to generate a series co-prime relation numbers is the basic task. So comes out of this basic method

coprime_checker.py

#if the return is 1, the a b are in coprime relation
#else return the smallest common divisor
def checker(a,b):
  while True:
    c = a%b
    if c == 0:
      return b
    a = b
    b = c

def checker(a,b):
if a<=b:
return all([b%i for i in xrange(2,a)])
return False