python: how to identify if a variable is an array or a scalar

I have a function that takes the argument NBins. I want to make a call to this function with a scalar 50 or an array [0, 10, 20, 30]. How can I identify within the function, what the length of NBins is? or said differently, if it is a scalar or a vector?

I tried this:

>>> N=[2,3,5]
>>> P = 5
>>> len(N)
3
>>> len(P)
Traceback (most recent call last):
  File "", line 1, in 
TypeError: object of type 'int' has no len()
>>> 

As you see, I can't apply len to P, since it's not an array.... Is there something like isarray or isscalar in python?

thanks