@ ProgramNode (location: (1,0)-(9,18))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(9,18))
    └── body: (length: 5)
        ├── @ DefNode (location: (1,0)-(1,18))
        │   ├── name: :foo
        │   ├── name_loc: (1,10)-(1,13) = "foo"
        │   ├── receiver:
        │   │   @ ParenthesesNode (location: (1,4)-(1,9))
        │   │   ├── body:
        │   │   │   @ CallNode (location: (1,5)-(1,8))
        │   │   │   ├── flags: variable_call, ignore_visibility
        │   │   │   ├── receiver: ∅
        │   │   │   ├── call_operator_loc: ∅
        │   │   │   ├── name: :foo
        │   │   │   ├── message_loc: (1,5)-(1,8) = "foo"
        │   │   │   ├── opening_loc: ∅
        │   │   │   ├── arguments: ∅
        │   │   │   ├── closing_loc: ∅
        │   │   │   └── block: ∅
        │   │   ├── opening_loc: (1,4)-(1,5) = "("
        │   │   └── closing_loc: (1,8)-(1,9) = ")"
        │   ├── parameters: ∅
        │   ├── body: ∅
        │   ├── locals: []
        │   ├── def_keyword_loc: (1,0)-(1,3) = "def"
        │   ├── operator_loc: (1,9)-(1,10) = "."
        │   ├── lparen_loc: ∅
        │   ├── rparen_loc: ∅
        │   ├── equal_loc: ∅
        │   └── end_keyword_loc: (1,15)-(1,18) = "end"
        ├── @ DefNode (location: (3,0)-(3,19))
        │   ├── name: :foo
        │   ├── name_loc: (3,11)-(3,14) = "foo"
        │   ├── receiver:
        │   │   @ ConstantReadNode (location: (3,4)-(3,10))
        │   │   └── name: :String
        │   ├── parameters: ∅
        │   ├── body: ∅
        │   ├── locals: []
        │   ├── def_keyword_loc: (3,0)-(3,3) = "def"
        │   ├── operator_loc: (3,10)-(3,11) = "."
        │   ├── lparen_loc: ∅
        │   ├── rparen_loc: ∅
        │   ├── equal_loc: ∅
        │   └── end_keyword_loc: (3,16)-(3,19) = "end"
        ├── @ DefNode (location: (5,0)-(5,20))
        │   ├── name: :foo
        │   ├── name_loc: (5,12)-(5,15) = "foo"
        │   ├── receiver:
        │   │   @ ConstantReadNode (location: (5,4)-(5,10))
        │   │   └── name: :String
        │   ├── parameters: ∅
        │   ├── body: ∅
        │   ├── locals: []
        │   ├── def_keyword_loc: (5,0)-(5,3) = "def"
        │   ├── operator_loc: (5,10)-(5,12) = "::"
        │   ├── lparen_loc: ∅
        │   ├── rparen_loc: ∅
        │   ├── equal_loc: ∅
        │   └── end_keyword_loc: (5,17)-(5,20) = "end"
        ├── @ DefNode (location: (7,0)-(7,17))
        │   ├── name: :foo
        │   ├── name_loc: (7,9)-(7,12) = "foo"
        │   ├── receiver:
        │   │   @ SelfNode (location: (7,4)-(7,8))
        │   ├── parameters: ∅
        │   ├── body: ∅
        │   ├── locals: []
        │   ├── def_keyword_loc: (7,0)-(7,3) = "def"
        │   ├── operator_loc: (7,8)-(7,9) = "."
        │   ├── lparen_loc: ∅
        │   ├── rparen_loc: ∅
        │   ├── equal_loc: ∅
        │   └── end_keyword_loc: (7,14)-(7,17) = "end"
        └── @ DefNode (location: (9,0)-(9,18))
            ├── name: :foo
            ├── name_loc: (9,10)-(9,13) = "foo"
            ├── receiver:
            │   @ SelfNode (location: (9,4)-(9,8))
            ├── parameters: ∅
            ├── body: ∅
            ├── locals: []
            ├── def_keyword_loc: (9,0)-(9,3) = "def"
            ├── operator_loc: (9,8)-(9,10) = "::"
            ├── lparen_loc: ∅
            ├── rparen_loc: ∅
            ├── equal_loc: ∅
            └── end_keyword_loc: (9,15)-(9,18) = "end"