Missing Key

The function word_frequency(words) should take a list of words and return a dictionary mapping each word to how many times it appears.

It crashes on the very first word every single time. The error happens on a line that looks perfectly logical.

Why does Python refuse to increment something that doesn't exist yet?

# your fix

+ must call get()

hint 2after hint 1

hint 3after hint 2

solution

Read the code. Before running anything: what does the last line below give?

def word_frequency(words):

"""

Returns a dictionary mapping each word to the number of times

it appears in the list.

Example: word_frequency(["a", "b", "a"]) -> {"a": 2, "b": 1}

"""

freq = {}

for word in words:

freq[word] += 1

return freq

>>> word_frequency(['a'])