@ ProgramNode (location: (1,0)-(3,8))
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(3,8))
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(3,8))
            ├── receiver:
            │   @ CallNode (location: (1,0)-(1,1))
            │   ├── receiver: ∅
            │   ├── call_operator_loc: ∅
            │   ├── message_loc: (1,0)-(1,1) = "h"
            │   ├── opening_loc: ∅
            │   ├── arguments: ∅
            │   ├── closing_loc: ∅
            │   ├── block: ∅
            │   ├── flags: variable_call
            │   └── name: :h
            ├── call_operator_loc: ∅
            ├── message_loc: (1,1)-(1,4) = "[k]"
            ├── opening_loc: (1,1)-(1,2) = "["
            ├── arguments:
            │   @ ArgumentsNode (location: (1,2)-(3,8))
            │   ├── arguments: (length: 2)
            │   │   ├── @ CallNode (location: (1,2)-(1,3))
            │   │   │   ├── receiver: ∅
            │   │   │   ├── call_operator_loc: ∅
            │   │   │   ├── message_loc: (1,2)-(1,3) = "k"
            │   │   │   ├── opening_loc: ∅
            │   │   │   ├── arguments: ∅
            │   │   │   ├── closing_loc: ∅
            │   │   │   ├── block: ∅
            │   │   │   ├── flags: variable_call
            │   │   │   └── name: :k
            │   │   └── @ BeginNode (location: (1,5)-(3,8))
            │   │       ├── begin_keyword_loc: (1,5)-(1,10) = "begin"
            │   │       ├── statements:
            │   │       │   @ StatementsNode (location: (2,7)-(2,9))
            │   │       │   └── body: (length: 1)
            │   │       │       └── @ IntegerNode (location: (2,7)-(2,9))
            │   │       │           └── flags: decimal
            │   │       ├── rescue_clause: ∅
            │   │       ├── else_clause: ∅
            │   │       ├── ensure_clause: ∅
            │   │       └── end_keyword_loc: (3,5)-(3,8) = "end"
            │   └── flags: ∅
            ├── closing_loc: (1,3)-(1,4) = "]"
            ├── block: ∅
            ├── flags: ∅
            └── name: :[]=
