andy formless fo _ _123 _abc ab123
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_

# expect: IDENTIFIER andy null
# expect: IDENTIFIER formless null
# expect: IDENTIFIER fo null
# expect: IDENTIFIER _ null
# expect: IDENTIFIER _123 null
# expect: IDENTIFIER _abc null
# expect: IDENTIFIER ab123 null
# expect: IDENTIFIER abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_ null
# expect: EOF  null