$s->select(read,write,error[,timeout])
Static method; call it with the package
name like new. read, write, and error
are either undef or
IO::Select objects. The optional argument timeout has the same effect
as for the core select call.
Returns an array of three elements, each a reference to an array, or an empty array on error. The arrays hold the handles that are ready for reading, ready for writing, and have error conditions, respectively.