from ctypes import *

p1 = pointer(c_long(10))                        # x=10; p1=&x;
pointer(p1)[0].contents = c_long(20)            # y=20; (&x)[0]=&y;

# the following might be expected to print 20 twice
print p1[0]                                     # p1[0];         or *p1;
print pointer(p1)[0][0]                         # (&p1)[0][0];   or **(&p1);