If( boolNode, method ) {

		const methodNode = new ShaderNode( method );
		this._currentCond = select( boolNode, methodNode );

		return this.add( this._currentCond );

	}
Represent an `if` statement in TSL.

@param {Node} boolNode - Represents the condition.
@param {Function} method - TSL code which is executed if the condition evaluates to `true`.
@return {StackNode} A reference to this stack node.