code: public Object expand(Context activeCtx, Object element) throws JsonLdError {
          return expand(activeCtx, null, element);
      }
docs: Expansion Algorithm
  
  http://json-ld.org/spec/latest/json-ld-api/#expansion-algorithm
  
  @param activeCtx
  The Active Context
  @param element
  The current element
  @return The expanded JSON-LD object.
  @throws JsonLdError
  If there was an error during expansion.