=========================================
Empty bracket argument [bracket_argument]
=========================================

message([[]])

---
(source_file
 (command_invocation
  (normal_command
   (identifier)
   (arguments
    (argument (bracket_argument))
   )
  )
 )
 )

=======================================
One bracket argument [bracket_argument]
=======================================

message([[An argument]])

---
(source_file
 (command_invocation
  (normal_command
   (identifier)
   (arguments
    (argument (bracket_argument (bracket_content)))
   )
  )
 )
 )

========================================
Two bracket arguments [bracket_argument]
========================================

message([[First argument]] [[Second argument]])

---
(source_file
 (command_invocation
  (normal_command
   (identifier)
   (arguments
    (argument (bracket_argument (bracket_content)))
    (seperation (space))
    (argument (bracket_argument (bracket_content)))
   )
  )
 )
 )

========================================================
Two bracket with two equals arguments [bracket_argument]
========================================================

message(
  [====[First argument]====]
  [====[Second argument]====]
)

---
(source_file
 (command_invocation
  (normal_command
   (identifier)
   (seperation (space))
   (arguments
    (argument (bracket_argument (bracket_content)))
    (seperation (space))
    (argument (bracket_argument (bracket_content)))
    (seperation (line_ending (newline)))
   )
  )
 )
 )

===================================================
Bracket argument with line break [bracket_argument]
===================================================

message([[An argument
with line break
]])

---
(source_file
 (command_invocation
  (normal_command
   (identifier)
   (arguments
    (argument (bracket_argument (bracket_content)))
   )
  )
 )
 )