@ ProgramNode (location: (1,0)-(26,3))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(26,3))
    └── body: (length: 6)
        ├── @ CallNode (location: (1,0)-(2,3))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :foo
        │   ├── message_loc: (1,0)-(1,3) = "foo"
        │   ├── opening_loc: ∅
        │   ├── arguments: ∅
        │   ├── closing_loc: ∅
        │   └── block:
        │       @ BlockNode (location: (1,4)-(2,3))
        │       ├── locals: []
        │       ├── parameters: ∅
        │       ├── body: ∅
        │       ├── opening_loc: (1,4)-(1,6) = "do"
        │       └── closing_loc: (2,0)-(2,3) = "end"
        ├── @ CallNode (location: (4,0)-(6,3))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :foo
        │   ├── message_loc: (4,0)-(4,3) = "foo"
        │   ├── opening_loc: ∅
        │   ├── arguments: ∅
        │   ├── closing_loc: ∅
        │   └── block:
        │       @ BlockNode (location: (4,4)-(6,3))
        │       ├── locals: []
        │       ├── parameters: ∅
        │       ├── body:
        │       │   @ BeginNode (location: (4,4)-(6,3))
        │       │   ├── begin_keyword_loc: ∅
        │       │   ├── statements: ∅
        │       │   ├── rescue_clause:
        │       │   │   @ RescueNode (location: (5,0)-(5,6))
        │       │   │   ├── keyword_loc: (5,0)-(5,6) = "rescue"
        │       │   │   ├── exceptions: (length: 0)
        │       │   │   ├── operator_loc: ∅
        │       │   │   ├── reference: ∅
        │       │   │   ├── statements: ∅
        │       │   │   └── consequent: ∅
        │       │   ├── else_clause: ∅
        │       │   ├── ensure_clause: ∅
        │       │   └── end_keyword_loc: (6,0)-(6,3) = "end"
        │       ├── opening_loc: (4,4)-(4,6) = "do"
        │       └── closing_loc: (6,0)-(6,3) = "end"
        ├── @ CallNode (location: (8,0)-(11,3))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :foo
        │   ├── message_loc: (8,0)-(8,3) = "foo"
        │   ├── opening_loc: ∅
        │   ├── arguments: ∅
        │   ├── closing_loc: ∅
        │   └── block:
        │       @ BlockNode (location: (8,4)-(11,3))
        │       ├── locals: []
        │       ├── parameters: ∅
        │       ├── body:
        │       │   @ StatementsNode (location: (9,2)-(10,5))
        │       │   └── body: (length: 2)
        │       │       ├── @ RescueModifierNode (location: (9,2)-(9,16))
        │       │       │   ├── expression:
        │       │       │   │   @ NilNode (location: (9,2)-(9,5))
        │       │       │   ├── keyword_loc: (9,6)-(9,12) = "rescue"
        │       │       │   └── rescue_expression:
        │       │       │       @ NilNode (location: (9,13)-(9,16))
        │       │       └── @ NilNode (location: (10,2)-(10,5))
        │       ├── opening_loc: (8,4)-(8,6) = "do"
        │       └── closing_loc: (11,0)-(11,3) = "end"
        ├── @ CallNode (location: (13,0)-(14,3))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :foo
        │   ├── message_loc: (13,0)-(13,3) = "foo"
        │   ├── opening_loc: ∅
        │   ├── arguments: ∅
        │   ├── closing_loc: ∅
        │   └── block:
        │       @ BlockNode (location: (13,4)-(14,3))
        │       ├── locals: [:a]
        │       ├── parameters:
        │       │   @ BlockParametersNode (location: (13,7)-(13,10))
        │       │   ├── parameters:
        │       │   │   @ ParametersNode (location: (13,8)-(13,9))
        │       │   │   ├── requireds: (length: 1)
        │       │   │   │   └── @ RequiredParameterNode (location: (13,8)-(13,9))
        │       │   │   │       ├── flags: ∅
        │       │   │   │       └── name: :a
        │       │   │   ├── optionals: (length: 0)
        │       │   │   ├── rest: ∅
        │       │   │   ├── posts: (length: 0)
        │       │   │   ├── keywords: (length: 0)
        │       │   │   ├── keyword_rest: ∅
        │       │   │   └── block: ∅
        │       │   ├── locals: (length: 0)
        │       │   ├── opening_loc: (13,7)-(13,8) = "|"
        │       │   └── closing_loc: (13,9)-(13,10) = "|"
        │       ├── body: ∅
        │       ├── opening_loc: (13,4)-(13,6) = "do"
        │       └── closing_loc: (14,0)-(14,3) = "end"
        ├── @ CallNode (location: (16,0)-(20,3))
        │   ├── flags: ignore_visibility
        │   ├── receiver: ∅
        │   ├── call_operator_loc: ∅
        │   ├── name: :foo
        │   ├── message_loc: (16,0)-(16,3) = "foo"
        │   ├── opening_loc: (16,3)-(16,4) = "("
        │   ├── arguments:
        │   │   @ ArgumentsNode (location: (16,4)-(16,10))
        │   │   ├── flags: ∅
        │   │   └── arguments: (length: 1)
        │   │       └── @ StringNode (location: (16,4)-(16,10))
        │   │           ├── flags: ∅
        │   │           ├── opening_loc: (16,4)-(16,10) = "<<-DOC"
        │   │           ├── content_loc: (17,0)-(18,0) = "  b\n"
        │   │           ├── closing_loc: (18,0)-(19,0) = "DOC\n"
        │   │           └── unescaped: "  b\n"
        │   ├── closing_loc: (16,10)-(16,11) = ")"
        │   └── block:
        │       @ BlockNode (location: (16,12)-(20,3))
        │       ├── locals: [:a]
        │       ├── parameters:
        │       │   @ BlockParametersNode (location: (16,15)-(16,18))
        │       │   ├── parameters:
        │       │   │   @ ParametersNode (location: (16,16)-(16,17))
        │       │   │   ├── requireds: (length: 1)
        │       │   │   │   └── @ RequiredParameterNode (location: (16,16)-(16,17))
        │       │   │   │       ├── flags: ∅
        │       │   │   │       └── name: :a
        │       │   │   ├── optionals: (length: 0)
        │       │   │   ├── rest: ∅
        │       │   │   ├── posts: (length: 0)
        │       │   │   ├── keywords: (length: 0)
        │       │   │   ├── keyword_rest: ∅
        │       │   │   └── block: ∅
        │       │   ├── locals: (length: 0)
        │       │   ├── opening_loc: (16,15)-(16,16) = "|"
        │       │   └── closing_loc: (16,17)-(16,18) = "|"
        │       ├── body:
        │       │   @ StatementsNode (location: (19,2)-(19,3))
        │       │   └── body: (length: 1)
        │       │       └── @ LocalVariableReadNode (location: (19,2)-(19,3))
        │       │           ├── name: :a
        │       │           └── depth: 0
        │       ├── opening_loc: (16,12)-(16,14) = "do"
        │       └── closing_loc: (20,0)-(20,3) = "end"
        └── @ CallNode (location: (22,0)-(26,3))
            ├── flags: ignore_visibility
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── name: :foo
            ├── message_loc: (22,0)-(22,3) = "foo"
            ├── opening_loc: (22,3)-(22,4) = "("
            ├── arguments:
            │   @ ArgumentsNode (location: (22,4)-(22,10))
            │   ├── flags: ∅
            │   └── arguments: (length: 1)
            │       └── @ StringNode (location: (22,4)-(22,10))
            │           ├── flags: ∅
            │           ├── opening_loc: (22,4)-(22,10) = "<<-DOC"
            │           ├── content_loc: (23,0)-(24,0) = "  b\n"
            │           ├── closing_loc: (24,0)-(25,0) = "DOC\n"
            │           └── unescaped: "  b\n"
            ├── closing_loc: (22,10)-(22,11) = ")"
            └── block:
                @ BlockNode (location: (22,12)-(26,3))
                ├── locals: []
                ├── parameters: ∅
                ├── body:
                │   @ StatementsNode (location: (25,2)-(25,3))
                │   └── body: (length: 1)
                │       └── @ CallNode (location: (25,2)-(25,3))
                │           ├── flags: variable_call, ignore_visibility
                │           ├── receiver: ∅
                │           ├── call_operator_loc: ∅
                │           ├── name: :a
                │           ├── message_loc: (25,2)-(25,3) = "a"
                │           ├── opening_loc: ∅
                │           ├── arguments: ∅
                │           ├── closing_loc: ∅
                │           └── block: ∅
                ├── opening_loc: (22,12)-(22,14) = "do"
                └── closing_loc: (26,0)-(26,3) = "end"