module ActiveFedora::SemanticNode::ClassMethods

@throws UnregisteredPredicateError if the predicate is a symbol but is not found in the PREDICATE_MAPPINGS
If predicate is not a Symbol, returns the predicate untouched
If predicate is a symbol, looks up the predicate in the PREDICATE_MAPPINGS

def predicate_lookup(predicate)
  if predicate.class == Symbol 
    if PREDICATE_MAPPINGS.has_key?(predicate)
      return PREDICATE_MAPPINGS[predicate]
    else
      throw UnregisteredPredicateError
    end
  end
  return predicate
end