Enable Javascript in your browser and then refresh this page, for a much enhanced experience.
Clearly Documented solution in Clear category for Non-unique Elements by m-gilbert
def checkio(data):
new = [] # create an empty list
for x in data: # iterate through our passed in list
if data.count(x) > 1: # if there is more than one occurence of an element
new.append(x) # append it to our list
return new
April 26, 2016