anchor.diff:                  matcher.FailureMsgForShould
           createMatcher f msg
   
  -let containing expected =
  -    createMatcher
  -        (fun (a:string) -> a.Contains(expected))
  -        (sprintf "contain %s" expected)
  -
  -// TODO: Delete
  -let contain = containing
  -
   let fail =
       let f a =
           try
  
positive.code:             (sprintf "be false")
  
      module string =
          let matching pattern =
              let regex = System.Text.RegularExpressions.Regex pattern
              createMatcher
  
negative.code:             (sprintf "throw exception with message %s" matcher.FailureMsgForShould)
              
      let withMessageContaining msg =
          withMessage (be.string.containing msg)
      
  let shouldNot<'T> (matcher:Matcher<'T>) (actual:'T) =
      let continuation = function
  