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Predicate open_hook/6
 iostream:open_hook(+Spec, +Mode, -Stream, -Close, +Options0, -Options) is semidet[multifile, library(http/http_open)]
Hook implementation that makes open_any/5 support http and https URLs for Mode == read.
 open_hook(+Spec, +Mode, -Stream, -Close, +Options0, -Options) is semidet[multifile, library(iostream)]
Open Spec in Mode, producing Stream.
Arguments:
Close- is unified to a goal that must be called to undo the side-effects of the action, e.g., typically the term close(Stream)
Options0- are the options passed to open_any/5
Options- are passed to the post processing filters that may be installed by open_any/5.