     
     { { 1 2 { 3 { 4 } 5 } } } [
         "(list 1 2 (list 3 (list 4) 5))" lisp-eval cons>seq
+    ] unit-test
+
+    { T{ lisp-symbol f "begin" } } [
+        "(defmacro begin (&rest body) (list (list (quote lambda) (list) body)))" lisp-eval
+    ] unit-test
+    
+    { t } [
+        T{ lisp-symbol f "begin" } lisp-macro?
+    ] unit-test
+    
+    { 5 } [
+        "(begin (+ 1 4))" lisp-eval
     ] unit-test
     
     { T{ lisp-symbol f "if" } } [

    ] unit-test
    
    { 1 } [
      "(if #t 1 2)" lisp-eval
    ] unit-test
    
    { 3 } [
       "((lambda (x) (if x (begin (+ 1 2)) (- 3 5))) #t)" lisp-eval
    ] unit-test
    
] with-interactive-vocabs

    "(lambda (&rest xs) xs)" lisp-string>factor "list" lisp-define
        
    { 5 } [
        "(+ 2 3)" lisp-eval
    ] unit-test
    
    { 8.3 } [
        "(- 10.4 2.1)" lisp-eval
    ] unit-test
    
    { 3 } [
        "((lambda (x y) (+ x y)) 1 2)" lisp-eval
    ] unit-test
    
    { 42 } [
        "((lambda (x y z) (+ x (- y z))) 40 3 1)" lisp-eval
    ] unit-test
    
    { "b" } [
        "(cond (#f \"a\") (#t \"b\"))" lisp-eval
    ] unit-test
    
    { "b" } [
        "(cond ((< 1 2) \"b\") (#t \"a\"))" lisp-eval
    ] unit-test
        
    { +nil+ } [
        "(list)" lisp-eval
    ] unit-test
    
    { { 1 2 3 4 5 } } [
