5 replaced http://codegolf.stackexchange.com/ with https://codegolf.stackexchange.com/

## C#6, 201 bytes, by milkby milk

using System.Linq;
_=>string./**/
#if trueJoin
(/*"*//*/""/**//*/"*/",
#else
Concat(//*/,
#endif
from m in" "let p=$@"{@" "}"from i in(_.Replace(p,@""))where!new[]{p^32^10}.Contains(i)select@i);  repl.it demo trueJoin is not defined, so only string.Concat() remains. p is "\n". p^32^10 is space. It would have been (a bit) more difficult if it's p^42 or other similar constants. ## C#6, 201 bytes, by milk using System.Linq; _=>string./**/ #if trueJoin (/*"*//*/""/**//*/"*/", #else Concat(//*/, #endif from m in" "let p=$@"{@"
"}"from i in(_.Replace(p,@""))where!new[]{p^32^10}.Contains(i)select@i);


repl.it demo

trueJoin is not defined, so only string.Concat() remains.
p is "\n". p^32^10 is space. It would have been (a bit) more difficult if it's p^42 or other similar constants.

## C#6, 201 bytes, by milk

using System.Linq;
_=>string./**/
#if trueJoin
(/*"*//*/""/**//*/"*/",
#else
Concat(//*/,
#endif
from m in" "let p=$@"{@" "}"from i in(_.Replace(p,@""))where!new[]{p^32^10}.Contains(i)select@i);  repl.it demo trueJoin is not defined, so only string.Concat() remains. p is "\n". p^32^10 is space. It would have been (a bit) more difficult if it's p^42 or other similar constants. 4 added 2 characters in body ## C#6, 201 bytes, by milk using System.Linq; _=>string./**/ #if trueJoin (/*"*//*/""/**//*/"*/", #else Concat(//*/, #endif from m in" "let p=$@"{@"
"}"from i in(_.Replace(p,@""))where!new[]{p^32^10}.Contains(i)select@i);


repl.it demo

trueJoin is not defined, so only string.JoinConcat() remains.
p is "\n". p^32^10 is space. It would have been (a bit) more difficult if it's p^42 or other similar constants.

## C#6, 201 bytes, by milk

using System.Linq;
_=>string./**/
#if trueJoin
(/*"*//*/""/**//*/"*/",
#else
Concat(//*/,
#endif
from m in" "let p=$@"{@" "}"from i in(_.Replace(p,@""))where!new[]{p^32^10}.Contains(i)select@i);  repl.it demo trueJoin is not defined, so only string.Join() remains. p is "\n". p^32^10 is space. It would have been (a bit) more difficult if it's p^42 or other similar constants. ## C#6, 201 bytes, by milk using System.Linq; _=>string./**/ #if trueJoin (/*"*//*/""/**//*/"*/", #else Concat(//*/, #endif from m in" "let p=$@"{@"
"}"from i in(_.Replace(p,@""))where!new[]{p^32^10}.Contains(i)select@i);


repl.it demo

trueJoin is not defined, so only string.Concat() remains.
p is "\n". p^32^10 is space. It would have been (a bit) more difficult if it's p^42 or other similar constants.

3 added 1 character in body

## C#C#6, 201 bytes, by milk

using System.Linq;
_=>string./**/
#if trueJoin
(/*"*//*/""/**//*/"*/",
#else
Concat(//*/,
#endif
from m in" "let p=$@"{@" "}"from i in(_.Replace(p,@""))where!new[]{p^32^10}.Contains(i)select@i);  repl.it demo trueJoin is not defined, so only string.Join() remains. p is "\n". p^32^10 is space. It would have been (a bit) more difficult if it's p^42 or other similar constants. ## C#, 201 bytes, by milk using System.Linq; _=>string./**/ #if trueJoin (/*"*//*/""/**//*/"*/", #else Concat(//*/, #endif from m in" "let p=$@"{@"
"}"from i in(_.Replace(p,@""))where!new[]{p^32^10}.Contains(i)select@i);


repl.it demo

trueJoin is not defined, so only string.Join() remains.
p is "\n". p^32^10 is space. It would have been (a bit) more difficult if it's p^42 or other similar constants.

## C#6, 201 bytes, by milk

using System.Linq;
_=>string./**/
#if trueJoin
(/*"*//*/""/**//*/"*/",
#else
Concat(//*/,
#endif
from m in" "let p=\$@"{@"
"}"from i in(_.Replace(p,@""))where!new[]{p^32^10}.Contains(i)select@i);


repl.it demo

trueJoin is not defined, so only string.Join() remains.
p is "\n". p^32^10 is space. It would have been (a bit) more difficult if it's p^42 or other similar constants.

2 added 194 characters in body
1