@ ProgramNode (location: (1,0)-(7,10))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(7,10))
    └── body: (length: 4)
        ├── @ CallNode (location: (1,0)-(1,10))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :fun
        │   ├── message_loc: (1,0)-(1,3) = "fun"
        │   ├── opening_loc: ∅
        │   ├── arguments: ∅
        │   ├── closing_loc: ∅
        │   └── block:
        │       @ BlockNode (location: (1,4)-(1,10))
        │       ├── locals: []
        │       ├── parameters: ∅
        │       ├── body: ∅
        │       ├── opening_loc: (1,4)-(1,6) = "do"
        │       └── closing_loc: (1,7)-(1,10) = "end"
        ├── @ CallNode (location: (3,0)-(3,7))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :fun
        │   ├── message_loc: (3,0)-(3,3) = "fun"
        │   ├── opening_loc: ∅
        │   ├── arguments: ∅
        │   ├── closing_loc: ∅
        │   └── block:
        │       @ BlockNode (location: (3,4)-(3,7))
        │       ├── locals: []
        │       ├── parameters: ∅
        │       ├── body: ∅
        │       ├── opening_loc: (3,4)-(3,5) = "{"
        │       └── closing_loc: (3,6)-(3,7) = "}"
        ├── @ CallNode (location: (5,0)-(5,9))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :fun
        │   ├── message_loc: (5,0)-(5,3) = "fun"
        │   ├── opening_loc: (5,3)-(5,4) = "("
        │   ├── arguments: ∅
        │   ├── closing_loc: (5,4)-(5,5) = ")"
        │   └── block:
        │       @ BlockNode (location: (5,6)-(5,9))
        │       ├── locals: []
        │       ├── parameters: ∅
        │       ├── body: ∅
        │       ├── opening_loc: (5,6)-(5,7) = "{"
        │       └── closing_loc: (5,8)-(5,9) = "}"
        └── @ CallNode (location: (7,0)-(7,10))
            ├── flags: ignore_visibility
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── name: :fun
            ├── message_loc: (7,0)-(7,3) = "fun"
            ├── opening_loc: (7,3)-(7,4) = "("
            ├── arguments:
            │   @ ArgumentsNode (location: (7,4)-(7,5))
            │   ├── flags: ∅
            │   └── arguments: (length: 1)
            │       └── @ IntegerNode (location: (7,4)-(7,5))
            │           └── flags: decimal
            ├── closing_loc: (7,5)-(7,6) = ")"
            └── block:
                @ BlockNode (location: (7,7)-(7,10))
                ├── locals: []
                ├── parameters: ∅
                ├── body: ∅
                ├── opening_loc: (7,7)-(7,8) = "{"
                └── closing_loc: (7,9)-(7,10) = "}"
