The identifier name which is tested by the predicate.
ReadonlytypeThe type name identifier.
OptionaltargetThe type that the identifier is tested to be.
May be undefined if the type is of the form asserts val.
Will be defined if the type is of the form asserts val is string or val is string.
True if the type is of the form
asserts val is string, false if the type is of the formval is string