================================================================================
If then else
================================================================================

if 12 then 27 else 42

--------------------------------------------------------------------------------

(source_file
  (if_expression
    condition: (integer_literal)
    consequence: (integer_literal)
    alternative: (integer_literal)))

================================================================================
If then
================================================================================

if 12 then 27

--------------------------------------------------------------------------------

(source_file
  (if_expression
    condition: (integer_literal)
    consequence: (integer_literal)))

================================================================================
Dangling else
================================================================================

if 12 then if 27 then 42 else "nope"

--------------------------------------------------------------------------------

(source_file
  (if_expression
    condition: (integer_literal)
    consequence: (if_expression
      condition: (integer_literal)
      consequence: (integer_literal)
      alternative: (string_literal))))

================================================================================
While
================================================================================

while 12 do 27

--------------------------------------------------------------------------------

(source_file
  (while_expression
    condition: (integer_literal)
    body: (integer_literal)))

================================================================================
For
================================================================================

for i := 12 to nil do "42"

--------------------------------------------------------------------------------

(source_file
  (for_expression
    index: (identifier)
    start: (integer_literal)
    end: (nil_literal)
    body: (string_literal)))

================================================================================
For no index
================================================================================

for 12 to nil do "42"

--------------------------------------------------------------------------------

(source_file
  (ERROR
    (identifier)
    (identifier)
    (nil_literal))
  (string_literal))

================================================================================
For no end
================================================================================

for 12 do "42"

--------------------------------------------------------------------------------

(source_file
  (ERROR
    (identifier)
    (identifier))
  (string_literal))

================================================================================
For no body
================================================================================

for 12 to nil

--------------------------------------------------------------------------------

(source_file
  (ERROR
    (identifier)
    (identifier))
  (nil_literal))