A.15 library(dicts): Dict utilities
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Availability::- use_module(library(dicts)).(can be autoloaded)
Source[semidet]dicts_join(+Key, +DictsIn, -Dicts)
Join dicts in Dicts that have the same value for Key, provided they do not have conflicting values on other keys. For example: 
?- dicts_join(x, [r{x:1, y:2}, r{x:1, z:3}, r{x:2,y:4}], L).
L = [r{x:1, y:2, z:3}, r{x:2, y:4}].
Errors
existence_error(key, Key, Dict) if a dict in Dicts1 or Dicts2 does not contain Key.