=======================================
Unquoted generator expression [gen_exp]
=======================================
message($<>)

---

(source_file
  (normal_command
    (identifier)
    (argument_list
      (argument
        (unquoted_argument
        (gen_exp)
        )
      )
    )
  )
)

=====================================
Quoted generator expression [gen_exp]
=====================================
message("$<>")

---

(source_file
  (normal_command
    (identifier)
    (argument_list
      (argument
        (quoted_argument
        (quoted_element
          (gen_exp)
        )
        )
      )
    )
  )
)

=====================
No argument [gen_exp]
=====================
message($<ANGLE-R>)

---

(source_file
  (normal_command
    (identifier)
    (argument_list
      (argument
        (unquoted_argument
        (gen_exp
          (argument
          (unquoted_argument)
          )
        )
        )
      )
    )
  )
)

============================================
No argument with superfluous colon [gen_exp]
============================================
message($<ANGLE-R:>)

---

(source_file
  (normal_command
    (identifier)
    (argument_list
      (argument
        (unquoted_argument
          (gen_exp
            (argument
            (unquoted_argument)
            )
          )
        )
      )
    )
  )
)

======================
One argument [gen_exp]
======================
message($<BOOL:-NOTFOUND>)

---

(source_file
  (normal_command
    (identifier)
    (argument_list
      (argument
        (unquoted_argument
        (gen_exp
          (argument
          (unquoted_argument))
          (argument
          (unquoted_argument)
          )
        )
        )
      )
    )
  )
)

=======================
Two arguments [gen_exp]
=======================
message($<AND:TRUE,FALSE>)

---

(source_file
  (normal_command
    (identifier)
    (argument_list
      (argument
        (unquoted_argument
          (gen_exp
            (argument
            (unquoted_argument))
            (argument
            (unquoted_argument))
            (argument
            (unquoted_argument)
            )
          )
        )
      )
    )
  )
)