@ ProgramNode (location: (1,0)-(1,14))
├── flags: ∅
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(1,14))
    ├── flags: ∅
    └── body: (length: 1)
        └── @ InterpolatedStringNode (location: (1,0)-(1,14))
            ├── flags: newline
            ├── opening_loc: ∅
            ├── parts: (length: 2)
            │   ├── @ InterpolatedStringNode (location: (1,0)-(1,8))
            │   │   ├── flags: ∅
            │   │   ├── opening_loc: (1,0)-(1,1) = "\""
            │   │   ├── parts: (length: 2)
            │   │   │   ├── @ StringNode (location: (1,1)-(1,4))
            │   │   │   │   ├── flags: static_literal, frozen
            │   │   │   │   ├── opening_loc: ∅
            │   │   │   │   ├── content_loc: (1,1)-(1,4) = "foo"
            │   │   │   │   ├── closing_loc: ∅
            │   │   │   │   └── unescaped: "foo"
            │   │   │   └── @ EmbeddedVariableNode (location: (1,4)-(1,7))
            │   │   │       ├── flags: ∅
            │   │   │       ├── operator_loc: (1,4)-(1,5) = "#"
            │   │   │       └── variable:
            │   │   │           @ InstanceVariableReadNode (location: (1,5)-(1,7))
            │   │   │           ├── flags: ∅
            │   │   │           └── name: :@a
            │   │   └── closing_loc: (1,7)-(1,8) = "\""
            │   └── @ StringNode (location: (1,9)-(1,14))
            │       ├── flags: static_literal, frozen
            │       ├── opening_loc: (1,9)-(1,10) = "\""
            │       ├── content_loc: (1,10)-(1,13) = "bar"
            │       ├── closing_loc: (1,13)-(1,14) = "\""
            │       └── unescaped: "bar"
            └── closing_loc: ∅
