problem3.py

def is_palindromatic(num):
    '''returns true if passed int is palindromatic'''
    return str(num) == str(num)[::-1]
    
# Demonstrating my lazi--- I mean ability to reuse code
def palingen():
     '''go through all the ints, and yield the palindromatic ones'''
     val = -1
     while True:
         val += 1
         if is_palindromatic(val):
             yield val

def stop_at_value(stop_val, gen):
    '''stop returning values from a generator if value returned is greater than stop_val'''
    while True:
        val = gen.__next__()
        if val < stop_val:
            yield val
        else:
            return

answer = sum(stop_at_value(10000, palingen())) # => 545040