It’s Markdown syntax. You can actually format it nicely in a code block:

bool isEven( long long x ) {
  if ( x < 0 ) x = -x;
  if ( x == 1 )
    return false;
  if ( x == 2 )
    return true;
  return isEven( x - 2 );
}

You do that by adding ``` above and below it. To force single line breaks, you can terminate your sentences with two spaces, or a backslash.