@ ProgramNode (location: (1,0)-(1,27))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,27))
    └── body: (length: 1)
        └── @ UndefNode (location: (1,0)-(1,27))
            ├── names: (length: 3)
            │   ├── @ SymbolNode (location: (1,6)-(1,9))
            │   │   ├── flags: forced_us_ascii_encoding
            │   │   ├── opening_loc: ∅
            │   │   ├── value_loc: (1,6)-(1,9) = "foo"
            │   │   ├── closing_loc: ∅
            │   │   └── unescaped: "foo"
            │   ├── @ SymbolNode (location: (1,11)-(1,15))
            │   │   ├── flags: forced_us_ascii_encoding
            │   │   ├── opening_loc: (1,11)-(1,12) = ":"
            │   │   ├── value_loc: (1,12)-(1,15) = "bar"
            │   │   ├── closing_loc: ∅
            │   │   └── unescaped: "bar"
            │   └── @ InterpolatedSymbolNode (location: (1,17)-(1,27))
            │       ├── opening_loc: (1,17)-(1,19) = ":\""
            │       ├── parts: (length: 2)
            │       │   ├── @ StringNode (location: (1,19)-(1,22))
            │       │   │   ├── flags: frozen
            │       │   │   ├── opening_loc: ∅
            │       │   │   ├── content_loc: (1,19)-(1,22) = "foo"
            │       │   │   ├── closing_loc: ∅
            │       │   │   └── unescaped: "foo"
            │       │   └── @ EmbeddedStatementsNode (location: (1,22)-(1,26))
            │       │       ├── opening_loc: (1,22)-(1,24) = "\#{"
            │       │       ├── statements:
            │       │       │   @ StatementsNode (location: (1,24)-(1,25))
            │       │       │   └── body: (length: 1)
            │       │       │       └── @ IntegerNode (location: (1,24)-(1,25))
            │       │       │           ├── flags: decimal
            │       │       │           └── value: 1
            │       │       └── closing_loc: (1,25)-(1,26) = "}"
            │       └── closing_loc: (1,26)-(1,27) = "\""
            └── keyword_loc: (1,0)-(1,5) = "undef"