python_coroutine_example

import sys

def sub(instr):

    i = 0
    gput = put()
    gput.next()
    while True:

        c = instr[i] 
       
        if c == '.': break

        if c.isdigit():
            if instr[i+1] == '.':
                gput.send(c)
                i += 1
            else:
                n = int(c)            
                for j in range(n + 1):                
                    gput.send(instr[i+1])
                i += 2
        else:            
            gput.send(instr[i])
            i += 1

       
def put():
    m = 1

    while True:
        c = yield
        if m % 3:                        
            sys.stdout.write(c)
        else:
            sys.stdout.write(c)
            sys.stdout.write(" ")
        m += 1
        

# the string must be terminated by a period
sub("a2b5e3426fg0zyw3210pq89r.")
print '\n'