eukit.HttpGet: obtain url from runtime data
entangle.prepare: prepare a function to converter
entangle: apply prepare function in initiator
entangle: apply initiator to extended functions in entangle
entangle: remove contextof & use converter as call context
entangle.pick: change name this.next to this.descend
entangle: dynamically set next for an entangle instance (cascading)
entangle.fork: make use of .next function to collect values