len()
it will count the element in the list, tuple and string and dictionary, eg.
>>> mylist = [1,2,3] #list
>>> len(mylist)
3
>>> word = 'hello' # string
>>> len(word)
5
>>> vals = {'a':1,'b':2} #dictionary
>>> len(vals)
2
>>> tup = (4,5,6) # tuple
>>> len(tup)
3
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