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