For because?

Syntax hilighting editors (scite) usually highlight the matching parens, ... programmers usually add newlines ...

ppi_dumper knows everything, PPI easily gets you a neat tree, and you can easily adjust the whitespace to your liking ( ppix_regexp_strip_comments )

PPI::Statement
  PPI::Structure::List        ( ... )
    PPI::Statement::Expression
      PPI::Token::Word        'ab'
      PPI::Token::Whitespace          ' '
      PPI::Token::Operator    '+'
      PPI::Token::Whitespace          ' '
      PPI::Structure::List    ( ... )
        PPI::Statement::Expression
          PPI::Token::Word    'fun1'
          PPI::Structure::List        ( ... )
            PPI::Statement::Expression
              PPI::Token::Word        'fun2'
              PPI::Structure::List    ( ... )
                PPI::Statement::Expression
                  PPI::Token::Number          '3'
                  PPI::Token::Whitespace      ' '
                  PPI::Token::Operator        '+'
                  PPI::Token::Whitespace      ' '
                  PPI::Token::Word    'fun3'
                  PPI::Structure::List        ( ... )
                    PPI::Statement::Expression
                      PPI::Token::Number      '4'
                      PPI::Token::Whitespace          ' '
                      PPI::Token::Operator    '+'
                      PPI::Token::Whitespace          ' '
                      PPI::Structure::List    ( ... )
                        PPI::Statement::Expression
                          PPI::Token::Number          '5'
                          PPI::Token::Whitespace      ' '
                          PPI::Token::Operator        '+'
                          PPI::Token::Whitespace      ' '
                          PPI::Token::Number          '6'
  PPI::Token::Structure       ';'
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