def std_labels(matrix_dim):
    """
    Return the standard-matrix-basis labels based on a matrix dimension.

    Parameters
    ----------
    matrix_dim : int
        The matrix dimension of the basis to generate labels for (the
        number of rows or columns in a matrix).

    Returns
    -------
    list of strs
    """
    if matrix_dim == 0: return []
    if matrix_dim == 1: return ['']  # special case - use empty label instead of "I"
    return ["(%d,%d)" % (i, j) for i in range(matrix_dim) for j in range(matrix_dim)]