code: function chunksToSourceMap(chunks, cfg) {
      var loc
      var outLine   = 0
      var outColumn = 0
      var smap      = sourcemap.newSourceMap()
      var acc = ''
  
      chunks.forEach(function(chunk) {
          if (chunk.content === '\n') {
              outLine   = outLine + 1
              outColumn = 0
          }
          loc = chunk.loc
          if (loc) {
              smap.add(
                  // jison line tracking is 1 based,
                  // source maps reads it as 0 based
                  loc.firstLine - 1,
                  loc.firstColumn,
                  outLine,
                  outColumn
              )
          }
          if (chunk.content !== '\n') {
              outColumn = outColumn + chunk.content.length
          }
      })
  
      return smap.generate(cfg)
  }
docs: convert chunks to source map chunks array of chunks cfg    sourcemap config