Make Headers iterable if Symbol is available
Make Headers iterable if Symbol is available

benestudio/fetch,zebulonj/fetch-plus,snadn/fetch,snadn/fetch,JhansiYarnagula/dummy2,aleclarson/fetch,zebulonj/fetch-plus,benestudio/fetch,snadn/fetch,JhansiYarnagula/dummy2,zebulonj/fetch-plus,benestudio/fetch,snadn/fetch,JhansiYarnagula/dummy2,github/fetch