@ ProgramNode (location: (1,0)-(3,3))
├── flags: ∅
├── locals: []
└── statements:
    @ StatementsNode (location: (1,0)-(3,3))
    ├── flags: ∅
    └── body: (length: 1)
        └── @ CallNode (location: (1,0)-(3,3))
            ├── flags: newline, ignore_visibility
            ├── receiver: ∅
            ├── call_operator_loc: ∅
            ├── name: :x
            ├── message_loc: (1,0)-(1,1) = "x"
            ├── opening_loc: ∅
            ├── arguments: ∅
            ├── closing_loc: ∅
            └── block:
                @ BlockNode (location: (1,2)-(3,3))
                ├── flags: ∅
                ├── locals: []
                ├── parameters:
                │   @ ItParametersNode (location: (1,2)-(3,3))
                │   └── flags: ∅
                ├── body:
                │   @ StatementsNode (location: (2,2)-(2,4))
                │   ├── flags: ∅
                │   └── body: (length: 1)
                │       └── @ ItLocalVariableReadNode (location: (2,2)-(2,4))
                │           └── flags: newline
                ├── opening_loc: (1,2)-(1,4) = "do"
                └── closing_loc: (3,0)-(3,3) = "end"
