@ ProgramNode (location: (1,0)-(1,12))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,12))
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(1,12))
            ├── flags: ignore_visibility
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── name: :p
            ├── message_loc: (1,0)-(1,1) = "p"
            ├── opening_loc: ∅
            ├── arguments:
            │   @ ArgumentsNode (location: (1,2)-(1,12))
            │   ├── flags: ∅
            │   └── arguments: (length: 1)
            │       └── @ InterpolatedStringNode (location: (1,2)-(1,12))
            │           ├── flags: ∅
            │           ├── opening_loc: ∅
            │           ├── parts: (length: 2)
            │           │   ├── @ StringNode (location: (1,2)-(1,6))
            │           │   │   ├── flags: frozen
            │           │   │   ├── opening_loc: (1,2)-(1,6) = "<<~E"
            │           │   │   ├── content_loc: (2,0)-(3,0) = "  x\n"
            │           │   │   ├── closing_loc: (3,0)-(4,0) = "E\n"
            │           │   │   └── unescaped: "x\n"
            │           │   └── @ StringNode (location: (1,7)-(1,12))
            │           │       ├── flags: frozen
            │           │       ├── opening_loc: (1,7)-(1,8) = "\""
            │           │       ├── content_loc: (1,8)-(1,11) = "  y"
            │           │       ├── closing_loc: (1,11)-(1,12) = "\""
            │           │       └── unescaped: "  y"
            │           └── closing_loc: ∅
            ├── closing_loc: ∅
            └── block: ∅