ev/select

    cfunction

    (ev/select & clauses)

    Block until the first of several channel operations occur. Returns a
    tuple of the form [:give chan] or [:take chan x], where a :give tuple
    is the result of a write and :take tuple is the result of a write.
    Each clause must be either a channel (for a channel take operation)
    or a tuple [channel x] for a channel give operation. Operations are
    tried in order, such that the first clauses will take precedence over
    later clauses.