between-markers examples needs cleanup

I would like to give some feedback about ...

From: https://js.checkio.org/mission/between-markers/solve/

console.log(betweenMarkers()) // Unexpected example not mentioned in specs
assert.equal(betweenMarkers('What is >apple<', '>', '<'), 'apples') // Assert example incorrect

HTTP_USER_AGENT:

Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:59.0) Gecko/20100101 Firefox/59.0

Kind regards, ebaklund