instruction:
Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.
question:
michigan avenue is a major north-south street in chicago.
answer:
michigan avenue

question:
goldenrods are any of the about 150 species of weedy herbs that make up the genus solidago.
answer:
goldenrod

question:
the north london line is a railway line of the london overground.
answer:
north london line