Interface representing a query node.
| children | The node's children. Can be null. |
| identifier | A string representing this node and its children. |
| leaf | True if this node is a leaf. A leaf doesn't have any children. |
| parent | Parent of this node. Null if this node is the root. |
| skipped | True if this node is skipped during evaluation. A node can be skipped if the QueryEngine was configured to skip unsupported nodes instead of generating errors. |
| token | The token used to build this node. |
| type | The node's type. |
| QueryHashCode | Returns a hashcode for this node. Multiple nodes can have the same hashcode if they have the same identifier. |