@ ProgramNode (location: (1,0)-(1,8))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,8))
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(1,8))
            ├── flags: attribute_write
            ├── receiver:
            │   @ ConstantReadNode (location: (1,0)-(1,1))
            │   └── name: :A
            ├── call_operator_loc: (1,1)-(1,3) = "::"
            ├── name: :b=
            ├── message_loc: (1,3)-(1,4) = "b"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (1,7)-(1,8))
            │   ├── flags: ∅
            │   └── arguments: (length: 1)
            │       └── @ IntegerNode (location: (1,7)-(1,8))
            │           └── flags: decimal
            ├── closing_loc: ∅
            └── block: ∅
