SYNOPSIS
object snoop(object snooper)
object snoop(object snooper, object snoopee)
DESCRIPTION
Starts a snoop from 'snooper' on 'snoopee', or if 'snoopee' is not
given, terminates any snoop from 'snooper'.
Return 1 on success, -1 if a snooping loop would be caused, 0 for
any other failure.
The snoop is checked with the master object for validity.
It will also fail if a snoop would result in a recursive snoop action.
SEE ALSO
query_snoop(E)