TODO: write docs

TODO: write docs

TODO: write docs

As object-reference-or-fault, except value argument may also be a list of objects and/or object references.

If *reify-refs* is true, return the object at this target URI. Returns nil if

1. *reify-refs* is false;
2. the object was not found;
3. access to the object was not permitted.

Consequently, use with care.

If *reify-refs* is true, runs basic checks on the object at this target URI, if it is found, or a list containing a fault object with this severity and token if it is not.

Requirements of properties of object, cribbed from https://www.w3.org/TR/activitystreams-vocabulary/#properties

Note the following sub-key value types:

• :collection opposite of :functional: if true, value should be a collection (in the Clojure sense), not a single object;
• :functional if true, value should be a single object; if false, may be a single object or a sequence of objects, but each must pass validation checks;
• :if-invalid a sequence of two keywords, first indicating severity, second being a message key;
• :if-missing a sequence of two keywords, first indicating severity, second being a message key;
• :required a boolean, or a function of one argument returning a boolean, in which case the function will be applied to the object having the property;
• :validator a function of one argument returning a boolean, which will be applied to the value or values of the identified property.

Return a list of faults found in object x, or nil if none are.

If expected-type is also passed, verify that x has expected-type. expected-type may be passed as a string or as a set of strings. Detailed verification of the particular features of types is not done here.

If this value is either

1. an object of expected-type;
2. a URI referencing an object of expected-type; or
3. a link object referencing an object of expected-type

and no faults are returned from validating the linked object, then return nil; else return a sequence comprising a fault object with this severity and token, prepended to the faults returned.

As with has-type-or-fault (q.v.), expected-type may be passed as a string, as a set of strings, or nil (indicating the type of the referenced object should not be checked).

NOTE THAT if *reify-refs* is false, referenced objects will not actually be checked.

Return a lost of faults found on properties of the object x, or nil if none are.