[Home](./index.md) > [kibana-plugin-plugins-expressions-server](./kibana-plugin-plugins-expressions-server.md) > [ExpressionAstFunctionBuilder](./kibana-plugin-plugins-expressions-server.expressionastfunctionbuilder.md) > [toAst](./kibana-plugin-plugins-expressions-server.expressionastfunctionbuilder.toast.md) ## ExpressionAstFunctionBuilder.toAst property Converts function to an AST. `ExpressionAstFunction` Signature: ```typescript toAst: () => ExpressionAstFunction; ```