RPN calculation using Python

RPN.py

import re

def RPN(operation):
    s = []
    for el in operation.split(" "):
        if el.isdigit():
            s.append(el)
        elif re.match("[+,-,*,/]", el) and len(s) > 1:
            s.append(eval("%s %s %s" % ( s.pop(), el , s.pop() )))
        else:
            break
    return s.pop()

operation = "5 10 2 * +"
print RPN(operation)