/// <summary>
/// Adds a literal to the graph
/// </summary>
/// <param name="literal">The new literal to add.</param>
/// <exception cref="ArgumentException">A literal with the same value, datatype URI and language ID alreday exists in the graph.</exception>
public void AddLiteral(IOwlLiteral literal)
{
_literals.Add((OwlLiteral)literal);
}
/// <summary>
/// Adds a new node to the graph.
/// </summary>
/// <param name="node">An object that implements the IOwlNode interface. This is the new node to add.</param>
/// <exception cref="ArgumentException">A node with the same ID already exists in the Graph.</exception>
public void AddNode(IOwlNode node)
{
_nodes.Add((OwlNode)node);
}
