tree.js

{
  Expression: {
    BinaryExpression: {
      left: {
        LiteralExpression: {
          value: 12
        }
      },
      operator: '*',
      right: {
        BinaryExpression: {
          left: {
            LiteralExpression: {
              value: 10
            }
          },
          operator: '-',
          right: {
            LiteralExpression: {
              value: 20
            }
          }
        }
      }
    }
  }
}