"TypeError: 'set' object is not callable" in different iPython Installations

I have two iPython notebook installations. One on an AWS Micro Instance, the second using Anaconda on my Macbook (OS X Yosemite). I encountered a difference in the way both of them handle the following code:

my_list = [1, 2, 3, 0, 5, 10, 11, 1, 5]
your_list = [1, 2, 3, 0, 12, 13]
my_set = set(my_list)
your_set = set(your_list)
print my_set
print len(my_set)
print len(my_list)

On iPython-AWS, my output is:

set([0, 1, 2, 3, 5, 10, 11])
7
9

On iPython-Macbook, my output is:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-29-cd060f1b0bde> in <module>()
      1 my_list = [1, 2, 3, 0, 5, 10, 11, 1, 5]
      2 your_list = [1, 2, 3, 0, 12, 13]
----> 3 my_set = set(my_list)
      4 your_set = set(your_list)
      5 print my_set

TypeError: 'set' object is not callable

Additionally, these are the installation details, if relevant: 1. iPython on AWS Micro Instance: http://ift.tt/1JFR3ly

2. iPython Notebook on Macbook - http://ift.tt/1gelhm5

I cannot seem to find the reason for this difference, although I did come across many threads on Stackoverflow regarding the "TypeError: 'set' object is not callable" issue. I will appreciate any help in understanding why this is so, and if there is anything I can do to ensure my code runs on both installations.