Function identifiers

identifiers(objectIds, featureIds?): Identifiers
Creates an ID filter, which limits a result set to just the features whose ids match the ids represented by the ID filter.

An arbitrary number of IDs can be passed to the identifier method.
```
  identifiers( [3, 5, "seven"] );
```
Parameters
- objectIds: FeatureId[]
  An array containing id values: ResourceId values (OGC Filter ver. 2.0), or GmlObjectId values (OGC Filter ver. 1.0)
- OptionalfeatureIds: FeatureId[]
  An array containing FeatureId values (OGC Filter ver. 1.0 only).
Returns Identifiers
The ID filter

Throws
Error when provided input parameters are not arrays