@ ProgramNode (location: (1,0)-(1,25))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,25))
    └── body: (length: 1)
        └── @ NextNode (location: (1,0)-(1,25))
            ├── arguments:
            │   @ ArgumentsNode (location: (1,5)-(1,25))
            │   ├── flags: ∅
            │   └── arguments: (length: 1)
            │       └── @ CallNode (location: (1,5)-(1,25))
            │           ├── flags: ∅
            │           ├── receiver: ∅
            │           ├── call_operator_loc: ∅
            │           ├── name: :foo
            │           ├── message_loc: (1,5)-(1,8) = "foo"
            │           ├── opening_loc: ∅
            │           ├── arguments:
            │           │   @ ArgumentsNode (location: (1,9)-(1,12))
            │           │   ├── flags: ∅
            │           │   └── arguments: (length: 1)
            │           │       └── @ CallNode (location: (1,9)-(1,12))
            │           │           ├── flags: variable_call
            │           │           ├── receiver: ∅
            │           │           ├── call_operator_loc: ∅
            │           │           ├── name: :arg
            │           │           ├── message_loc: (1,9)-(1,12) = "arg"
            │           │           ├── opening_loc: ∅
            │           │           ├── arguments: ∅
            │           │           ├── closing_loc: ∅
            │           │           └── block: ∅
            │           ├── closing_loc: ∅
            │           └── block:
            │               @ BlockNode (location: (1,13)-(1,25))
            │               ├── locals: [:bar]
            │               ├── locals_body_index: 1
            │               ├── parameters:
            │               │   @ BlockParametersNode (location: (1,16)-(1,21))
            │               │   ├── parameters:
            │               │   │   @ ParametersNode (location: (1,17)-(1,20))
            │               │   │   ├── requireds: (length: 1)
            │               │   │   │   └── @ RequiredParameterNode (location: (1,17)-(1,20))
            │               │   │   │       └── name: :bar
            │               │   │   ├── optionals: (length: 0)
            │               │   │   ├── rest: ∅
            │               │   │   ├── posts: (length: 0)
            │               │   │   ├── keywords: (length: 0)
            │               │   │   ├── keyword_rest: ∅
            │               │   │   └── block: ∅
            │               │   ├── locals: (length: 0)
            │               │   ├── opening_loc: (1,16)-(1,17) = "|"
            │               │   └── closing_loc: (1,20)-(1,21) = "|"
            │               ├── body: ∅
            │               ├── opening_loc: (1,13)-(1,15) = "do"
            │               └── closing_loc: (1,22)-(1,25) = "end"
            └── keyword_loc: (1,0)-(1,4) = "next"
