""" This is a simple example of the use of Python's decorator syntax.
To keep it simple, trace does not work with functions called with
keyword arguments.  The output could be improved, also. """

def trace(f):
    def new_f(*args):
         print 'Entering %s%s' % (f.__name__, args)
         result = f(*args)
         print 'Exiting %s%s with %s' % (f.__name__, args, result)
         return result
    return new_f

@trace
def sum(n, m):
    return n + m

@trace
def fact(n):
  return 1 if n<2 else n * fact(n-1)