How do I say "Is this a function"?

[John Henry]

How do I determine is something a function?

For instance, I don't want to relying on exceptions below:

def f1():
   print "In f1"

def f3():
   print "In f3"

def others():
   print "In others"

for i in xrange(1,3):
   fct = "f%d()"%(i+1)
   try:
      exec fct
   except:
      others()

I wish to say:

   if value of fct is a funtion, invoke it, otherwise invoke others().

Thanks,