code: function minimizeCst(cstElement) {
              // tokenType idx is auto generated, can't assert over it
              if (cstElement.tokenType) {
                  delete cstElement.tokenType
              }
  
              // CstNode
              if (cstElement.children !== undefined) {
                  cstElement.children = _.omitBy(cstElement.children, _.isEmpty)
                  _.forEach(cstElement.children, childArr => {
                      _.forEach(childArr, minimizeCst)
                  })
              }
  
              return cstElement
          }
docs: to make it easier to understand the assertions