memo:
```bash
> ruby -e 'begin; 117; end.to_s' --parser=prism --dump=parsetree
@ ProgramNode (location: (1,0)-(1,20))
+-- locals: []
+-- statements:
    @ StatementsNode (location: (1,0)-(1,20))
    +-- body: (length: 1)
        +-- @ CallNode (location: (1,0)-(1,20))
            +-- CallNodeFlags: nil
            +-- receiver:
            |   @ BeginNode (location: (1,0)-(1,15))
            |   +-- begin_keyword_loc: (1,0)-(1,5) = "begin"
            |   +-- statements:
            |   |   @ StatementsNode (location: (1,7)-(1,10))
            |   |   +-- body: (length: 1)
            |   |       +-- @ IntegerNode (location: (1,7)-(1,10))
            |   |           +-- IntegerBaseFlags: decimal
            |   |           +-- value: 117
            |   +-- rescue_clause: nil
            |   +-- else_clause: nil
            |   +-- ensure_clause: nil
            |   +-- end_keyword_loc: (1,12)-(1,15) = "end"
            +-- call_operator_loc: (1,15)-(1,16) = "."
            +-- name: :to_s
            +-- message_loc: (1,16)-(1,20) = "to_s"
            +-- opening_loc: nil
            +-- arguments: nil
            +-- closing_loc: nil
            +-- equal_loc: nil
            +-- block: nil
```