# Functions
NewCrawler returns a new crawler instance.
# Interfaces
Graph is implemented by objects that can upsert links and edges into a link graph instance.
Indexer is implemented by objects that can index the contents of web-pages retrieved by the crawler pipeline.
PrivateNetworkDetector is implemented by objects that can detect whether a host resolves to a private network address.
URLGetter is implemented by objects that can perform HTTP GET requests.