@ ProgramNode (location: (0...26))
├── locals: []
└── statements:
    @ StatementsNode (location: (0...26))
    └── body: (length: 3)
        ├── @ YieldNode (location: (0...5))
        │   ├── keyword_loc: (0...5) = "yield"
        │   ├── lparen_loc: ∅
        │   ├── arguments: ∅
        │   └── rparen_loc: ∅
        ├── @ YieldNode (location: (6...14))
        │   ├── keyword_loc: (6...11) = "yield"
        │   ├── lparen_loc: (11...12) = "("
        │   ├── arguments:
        │   │   @ ArgumentsNode (location: (12...13))
        │   │   └── arguments: (length: 1)
        │   │       └── @ CallNode (location: (12...13))
        │   │           ├── receiver: ∅
        │   │           ├── call_operator_loc: ∅
        │   │           ├── message_loc: (12...13) = "a"
        │   │           ├── opening_loc: ∅
        │   │           ├── arguments: ∅
        │   │           ├── closing_loc: ∅
        │   │           ├── block: ∅
        │   │           ├── flags: variable_call
        │   │           └── name: "a"
        │   └── rparen_loc: (13...14) = ")"
        └── @ YieldNode (location: (15...26))
            ├── keyword_loc: (15...20) = "yield"
            ├── lparen_loc: (20...21) = "("
            ├── arguments:
            │   @ ArgumentsNode (location: (21...25))
            │   └── arguments: (length: 2)
            │       ├── @ CallNode (location: (21...22))
            │       │   ├── receiver: ∅
            │       │   ├── call_operator_loc: ∅
            │       │   ├── message_loc: (21...22) = "a"
            │       │   ├── opening_loc: ∅
            │       │   ├── arguments: ∅
            │       │   ├── closing_loc: ∅
            │       │   ├── block: ∅
            │       │   ├── flags: variable_call
            │       │   └── name: "a"
            │       └── @ CallNode (location: (24...25))
            │           ├── receiver: ∅
            │           ├── call_operator_loc: ∅
            │           ├── message_loc: (24...25) = "b"
            │           ├── opening_loc: ∅
            │           ├── arguments: ∅
            │           ├── closing_loc: ∅
            │           ├── block: ∅
            │           ├── flags: variable_call
            │           └── name: "b"
            └── rparen_loc: (25...26) = ")"
