Python 3 code. Please

Counting lngrams structions Forums Tutoring E Problem program.py 1 from collect1ons 1mport defaultdict as dd We begin with a feature extraction function. The features we are going to use are called trigrams. A trigram is simply a string of three contiguous characters. For example in the string"I love comput1ng", there are lots of trigrams (L- 2 to be precise, where L is the length of the string): " ",Lo","Lov"," first four of them, in sequence. 3 def count trigrams (document): count tr1grams takes a str1ng and returns a dict1onary of the counts of trigrams within the document. "n " your code here ve"] are the Write a function count trigrams (document) that takes a string and returns a default dictionary with the frequency counts of the trigrams within the string (noting that if you have N repeats of the same trigram in the string, the frequency will be N). Note that the output must be a default dictionary and not a standard dictionary, as it will be useful later. Note also that you should not modify the string in any way (eg, remove punctuation, remove whitespace or convert to lower case) in calculating the frequencies. Your code should behave as follows: >>>count trigrams ("hel") defaultd1ct(, {'hel. : 1.0)) >> count_trigrams ("aaaaa") defaultdict (, f'aaa 3.0H) >>> count trigrams ("Boaty mcBoatFace.") defaultdict (, f'ty1.0, Fac': 1.0