@ ProgramNode (location: (0...43))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...43))
    └── body: (length: 3)
        ├── @ CallNode (location: (0...14))
        │   ├── receiver:
        │   │   @ CallNode (location: (0...3))
        │   │   ├── receiver: ∅
        │   │   ├── call_operator_loc: ∅
        │   │   ├── message_loc: (0...3) = "foo"
        │   │   ├── opening_loc: ∅
        │   │   ├── arguments: ∅
        │   │   ├── closing_loc: ∅
        │   │   ├── block: ∅
        │   │   ├── flags: variable_call
        │   │   └── name: "foo"
        │   ├── call_operator_loc: (3...4) = "."
        │   ├── message_loc: (4...7) = "fun"
        │   ├── opening_loc: ∅
        │   ├── arguments:
        │   │   @ ArgumentsNode (location: (8...11))
        │   │   └── arguments: (length: 1)
        │   │       └── @ ParenthesesNode (location: (8...11))
        │   │           ├── body:
        │   │           │   @ StatementsNode (location: (9...10))
        │   │           │   └── body: (length: 1)
        │   │           │       └── @ IntegerNode (location: (9...10))
        │   │           │           └── flags: decimal
        │   │           ├── opening_loc: (8...9) = "("
        │   │           └── closing_loc: (10...11) = ")"
        │   ├── closing_loc: ∅
        │   ├── block:
        │   │   @ BlockNode (location: (12...14))
        │   │   ├── locals: []
        │   │   ├── parameters: ∅
        │   │   ├── body: ∅
        │   │   ├── opening_loc: (12...13) = "{"
        │   │   └── closing_loc: (13...14) = "}"
        │   ├── flags: ∅
        │   └── name: "fun"
        ├── @ CallNode (location: (16...31))
        │   ├── receiver:
        │   │   @ CallNode (location: (16...19))
        │   │   ├── receiver: ∅
        │   │   ├── call_operator_loc: ∅
        │   │   ├── message_loc: (16...19) = "foo"
        │   │   ├── opening_loc: ∅
        │   │   ├── arguments: ∅
        │   │   ├── closing_loc: ∅
        │   │   ├── block: ∅
        │   │   ├── flags: variable_call
        │   │   └── name: "foo"
        │   ├── call_operator_loc: (19...21) = "::"
        │   ├── message_loc: (21...24) = "fun"
        │   ├── opening_loc: ∅
        │   ├── arguments:
        │   │   @ ArgumentsNode (location: (25...28))
        │   │   └── arguments: (length: 1)
        │   │       └── @ ParenthesesNode (location: (25...28))
        │   │           ├── body:
        │   │           │   @ StatementsNode (location: (26...27))
        │   │           │   └── body: (length: 1)
        │   │           │       └── @ IntegerNode (location: (26...27))
        │   │           │           └── flags: decimal
        │   │           ├── opening_loc: (25...26) = "("
        │   │           └── closing_loc: (27...28) = ")"
        │   ├── closing_loc: ∅
        │   ├── block:
        │   │   @ BlockNode (location: (29...31))
        │   │   ├── locals: []
        │   │   ├── parameters: ∅
        │   │   ├── body: ∅
        │   │   ├── opening_loc: (29...30) = "{"
        │   │   └── closing_loc: (30...31) = "}"
        │   ├── flags: ∅
        │   └── name: "fun"
        └── @ CallNode (location: (33...43))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (33...36) = "fun"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (37...40))
            │   └── arguments: (length: 1)
            │       └── @ ParenthesesNode (location: (37...40))
            │           ├── body:
            │           │   @ StatementsNode (location: (38...39))
            │           │   └── body: (length: 1)
            │           │       └── @ IntegerNode (location: (38...39))
            │           │           └── flags: decimal
            │           ├── opening_loc: (37...38) = "("
            │           └── closing_loc: (39...40) = ")"
            ├── closing_loc: ∅
            ├── block:
            │   @ BlockNode (location: (41...43))
            │   ├── locals: []
            │   ├── parameters: ∅
            │   ├── body: ∅
            │   ├── opening_loc: (41...42) = "{"
            │   └── closing_loc: (42...43) = "}"
            ├── flags: ∅
            └── name: "fun"
