Concatenate two tokens. This takes two token elements in the same format returned by Tokenizer.tokenize(), and returns a combined element in the same format. The result should be as though the original pair of tokens had been concatenated in the input string.

Is the given token a word? This receives a token element in the same format returned by Tokenizer.tokenize(). Returns true if the token represents a word that could be looked up in the dictionary, nil if it's something else (such as punctuation, a number, or a quoted literal).

[Required]