@ ProgramNode (location: (2,0)-(2,3))
├── locals: []
└── statements:
    @ StatementsNode (location: (2,0)-(2,3))
    └── body: (length: 1)
        └── @ CallNode (location: (2,0)-(2,3))
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── message_loc: (2,0)-(2,1) = "p"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (2,2)-(2,3))
            │   ├── arguments: (length: 1)
            │   │   └── @ IntegerNode (location: (2,2)-(2,3))
            │   │       └── flags: decimal
            │   └── flags: ∅
            ├── closing_loc: ∅
            ├── block: ∅
            ├── flags: ∅
            └── name: :p
