StaticbindStaticgetStaticgetStaticrunRuns fn in a new context; the returned promise settles with fn. A nested run starts from the
values of the outer run (it sees the outer current context until it sets its own) and its changes
stay inside it: the semantics of 4.x, kept from cls-hooked.
StaticsetStaticset
fnruns incontext(the values of a run), by default the context active now.