===================================
Command invocation without argument
===================================

message()

---

(source_file
  (command_invocation
  (identifier)))

===============================================
Command invocation without argument with spaces
===============================================

message( )

---

(source_file
  (command_invocation
    (identifier)
    (seperation (space))
  )
)

================================================
Command invocation without argument with newline
================================================

message(

)

---

(source_file
  (command_invocation
    (identifier)
    (seperation
      (line_ending (newline))
    )
  )
)