Return the maximum of an array, ignoring any NaNs.

        :param a: The array.
        :return: The maximum value of the array

def fn_max(self, a, axis=None):
        """
        Return the maximum of an array, ignoring any NaNs.

        :param a: The array.
        :return: The maximum value of the array
        """

        return numpy.nanmax(self._to_ndarray(a), axis=axis)