@ ProgramNode (location: (0...41))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...41))
    └── body: (length: 4)
        ├── @ ReturnNode (location: (0...6))
        │   ├── keyword_loc: (0...6) = "return"
        │   └── arguments: ∅
        ├── @ ReturnNode (location: (8...18))
        │   ├── keyword_loc: (8...14) = "return"
        │   └── arguments:
        │       @ ArgumentsNode (location: (15...18))
        │       └── arguments: (length: 1)
        │           └── @ CallNode (location: (15...18))
        │               ├── receiver: ∅
        │               ├── call_operator_loc: ∅
        │               ├── message_loc: (15...18) = "foo"
        │               ├── opening_loc: ∅
        │               ├── arguments: ∅
        │               ├── closing_loc: ∅
        │               ├── block: ∅
        │               ├── flags: variable_call
        │               └── name: "foo"
        ├── @ ReturnNode (location: (20...28))
        │   ├── keyword_loc: (20...26) = "return"
        │   └── arguments:
        │       @ ArgumentsNode (location: (26...28))
        │       └── arguments: (length: 1)
        │           └── @ ParenthesesNode (location: (26...28))
        │               ├── body: ∅
        │               ├── opening_loc: (26...27) = "("
        │               └── closing_loc: (27...28) = ")"
        └── @ ReturnNode (location: (30...41))
            ├── keyword_loc: (30...36) = "return"
            └── arguments:
                @ ArgumentsNode (location: (36...41))
                └── arguments: (length: 1)
                    └── @ ParenthesesNode (location: (36...41))
                        ├── body:
                        │   @ StatementsNode (location: (37...40))
                        │   └── body: (length: 1)
                        │       └── @ CallNode (location: (37...40))
                        │           ├── receiver: ∅
                        │           ├── call_operator_loc: ∅
                        │           ├── message_loc: (37...40) = "foo"
                        │           ├── opening_loc: ∅
                        │           ├── arguments: ∅
                        │           ├── closing_loc: ∅
                        │           ├── block: ∅
                        │           ├── flags: variable_call
                        │           └── name: "foo"
                        ├── opening_loc: (36...37) = "("
                        └── closing_loc: (40...41) = ")"
