shebang_line ('#! [foo]')
WHITE_SPACE ('\n')
# ('#')
! ('!')
WHITE_SPACE (' ')
[ ('[')
identifier ('bar')
] (']')
WHITE_SPACE ('\n')
fn ('fn')
WHITE_SPACE (' ')
identifier ('main')
( ('(')
) (')')
WHITE_SPACE (' ')
{ ('{')
} ('}')
