anchor.diff:  
   [<Test>]
   [<Ignore("Remove to run test")>]
  +let ``One file, one match, print line numbers flag`` () =
  +    let pattern = "Forbidden"
  +    let flags = "-n"
  +    let files = [paradiseLostFileName]
  +
  +    let expected = 
  +        "2:Of that Forbidden Tree, whose mortal tast\n"
  +    
  +    Assert.That(grep pattern flags files, Is.EqualTo(expected))
  +
  +[<Test>]
  +[<Ignore("Remove to run test")>]
  +let ``One file, one match, case-insensitive flag`` () =
  +    let pattern = "Forbidden"
  +    let flags = "-i"
  +    let files = [paradiseLostFileName]
  +
  +    let expected = 
  +        "Of that Forbidden Tree, whose mortal tast\n"
  +    
  +    Assert.That(grep pattern flags files, Is.EqualTo(expected))
  +
  +[<Test>]
  +[<Ignore("Remove to run test")>]
  +let ``One file, one match, print file names flag`` () =
  +    let pattern = "Forbidden"
  +    let flags = "-l"
  +    let files = [paradiseLostFileName]
  +
  +    let expected = 
  +        sprintf "%s\n" paradiseLostFileName
  +    
  +    Assert.That(grep pattern flags files, Is.EqualTo(expected))
  +
  +[<Test>]
  +[<Ignore("Remove to run test")>]
  +let ``One file, one match, match entire lines flag`` () =
  +    let pattern = "With loss of Eden, till one greater Man"
  +    let flags = "-x"
  +    let files = [paradiseLostFileName]
  +
  +    let expected = 
  +        "With loss of Eden, till one greater Man\n"
  +    
  +    Assert.That(grep pattern flags files, Is.EqualTo(expected))
  +    
  +[<Test>]
  +[<Ignore("Remove to run test")>]
  +let ``One file, one match, multiple flags`` () =
  +    let pattern = "OF ATREUS, Agamemnon, KIng of MEN."
  +    let files = [iliadFileName]
  +    let flags = "-n -i -x"
  +    let expected = 
  +        "9:Of Atreus, Agamemnon, King of men.\n"
  +    
  +    Assert.That(grep pattern flags files, Is.EqualTo(expected))
  +
  +[<Test>]
  +[<Ignore("Remove to run test")>]
   let ``One file, several matches, no flags`` () =
       let pattern = "may"
       let flags = ""
  
positive.code:     
  [<Test>]
  [<Ignore("Remove to run test")>]
  let ``Multiple files, several matches, multiple flags`` () =
      let pattern = "WITH LOSS OF EDEN, TILL ONE GREATER MAN"
      let files = [iliadFileName; midsummerNightFileName; paradiseLostFileName]
      let flags = "-n -i -x"
  
negative.code:         "Restore us, and regain the blissful Seat,\n" + 
          "Sing Heav'nly Muse, that on the secret top\n" + 
          "That Shepherd, who first taught the chosen Seed\n"
      
      Assert.That(grep pattern flags files, Is.EqualTo(expected))
  
  