{"ast_node_type":"variable","tokens":[{"end":78,"kind":"keyword","start":0,"text":"let"}]}
                let operand = self.ecx.read_immediate(operand).discard_err()?;
                let operand = self.evaluated[operand].as_ref()?;
                let val = self.ecx.unary_op(un_op, &operand).discard_err()?;