    \documentclass{article}

    \usepackage{agda}

    \begin{document}

    \begin{code}
    postulate
      A  B
          C : Set
    \end{code}

    \begin{code}
    postulate
      D  E

          F : Set
    \end{code}

    \begin{code}
    postulate
      G  H  : Set
      I
          J : Set
    \end{code}

    \begin{AgdaMultiCode}
    \begin{code}
    postulate
      K  L
    \end{code}
    \begin{code}
          M : Set
    \end{code}
    \end{AgdaMultiCode}

    \begin{code}
    record R : Set₁ where
      field N :
                Set
    \end{code}

    % There is (and should be) trailing whitespace at the end of some
    % lines below.

    \begin{AgdaAlign}
    text \begin{code}
    module _ where
    \end{code} more text
        also text  \begin{code}
        postulate O : Set
      \end{code} text again

     text          \begin{code}
        postulate o : O
      \end{code}   text
    \end{AgdaAlign}

    \begin{code}
    postulate
     P : Set
    \end{code}

    \begin{code}
    module _ where
     postulate
      Q : Set
    \end{code}

    \begin{code}
    module _ where
             postulate
              S : Set
    \end{code}

    \begin{AgdaMultiCode}
    \begin{code}
    module _ where
    \end{code}
    \begin{code}
      postulate T : Set
                U : Set
    \end{code}
    \end{AgdaMultiCode}

    \begin{AgdaSuppressSpace}
    \begin{code}
    module _ where
    \end{code}
    \begin{code}
      postulate V : Set
                W : Set
    \end{code}
    \end{AgdaSuppressSpace}

    \begin{code}
    X : Set₁
    X =
      Set
    \end{code}

    \begin{code}
    Y : Set₁
    Y =       Set

    Zzzzzzzzz : Set → Set
    Zzzzzzzzz X
              = X
    \end{code}

    \end{document}