code: function merge (a, b) {
      var obj = JSON.parse(JSON.stringify(a))
      if (typeof a === 'object' && typeof b === 'object') {
        if (Array.isArray(a) && Array.isArray(b)) {
          for (var i in b) {
            obj.push(b[i])
          }
        } else {
          for (var i in b) {
            obj[i] = b[i]
          }
        }
      }
      return obj
    }
docs: Merge:  fuse object/array 'b' into 'a' and return
  
  @param {object/array} a, bottom item
  @param {object/array} b, top item
  @return {object/array} fuse(a <- b)