A.30 library(option): Option list processing
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Availability::- use_module(library(option)).(can be autoloaded)
Source[det]option(?Option, +Options, +Default)
Get an Option from Options. If Option does not appear in Options, unify the value with Default. If Option appears multiple times in Options, the first value is used. For example 
?- option(max_depth(D), [x(a), max_depth(20)], 10).
D = 20.
?- option(max_depth(D), [x(a)], 10).
D = 10.
Option Term of the form Name(?Value).
Options is a list of Name(Value) or Name=Value or a dict.