    \documentclass{article}
    \usepackage{agda}

    \begin{document}

    \begin{code}
    -- We use non-standard spaces between the name of the term and the
    -- colon.
    postulate
      s00A0 : Set  -- NO-BREAK SPACE        ("\ " with Agda input method)
      s2004 : Set  -- THREE-PER-EM SPACE    ("\;" with Agda input method)
      s202F : Set  -- NARROW NO-BREAK SPACE ("\," with Agda input method)
    \end{code}

    % Various whitespace characters: "    ".
    \begin{code}
    open import Agda.Builtin.String

    -- Various whitespace characters: "    ".

    various-whitespace-characters : String
    various-whitespace-characters = "    "
    \end{code}

    \end{document}