def arnonA_mono_to_string(mono, latex=False, p=2):
    """
    String representation of element of Arnon's A basis.

    This is used by the _repr_ and _latex_ methods.

    INPUT:

    -  ``mono`` - tuple of pairs of non-negative integers
       (m,k) with `m >= k`

    - ``latex`` - boolean (optional, default False), if true, output
      LaTeX string

    OUTPUT: ``string`` - concatenation of strings of the form
    ``X^{m}_{k}`` for each pair (m,k)

    EXAMPLES::

        sage: from sage.algebras.steenrod.steenrod_algebra_misc import arnonA_mono_to_string
        sage: arnonA_mono_to_string(((1,2),(3,0)))
        'X^{1}_{2} X^{3}_{0}'
        sage: arnonA_mono_to_string(((1,2),(3,0)),latex=True)
        'X^{1}_{2} X^{3}_{0}'

    The empty tuple represents the unit element::

        sage: arnonA_mono_to_string(())
        '1'
    """
    if len(mono) == 0:
        return "1"
    else:
        string = ""
        for (m,k) in mono:
            string = string + "X^{" + str(m) + "}_{" \
                + str(k) + "} "
        return string.strip(" ")