I'm using gensim to extract feature vector from a document.
I've downloaded the pre-trained model from Google named `GoogleNews-vectors-negative300.bin` and I loaded that model using the following command:

```
model = models.Doc2Vec.load_word2vec_format('GoogleNews-vectors-negative300.bin', binary=True)

```

My purpose is to get a feature vector from a document. For a word, it's very easy to get the corresponding vector:

```
vector = model[word]

```

However, I don't know how to do it for a document. Could you please help?