@staticmethod
def _check_band(label, band_definition):
    """Check that a proposed band definition is valid.

        Parameters
        ----------
        label : str
            The name of the new band.
        band_definition : tuple of (float, float)
            The lower and upper frequency limit of the band, in Hz.

        Raises
        ------
        ValueError
            If band definition is not properly formatted.
        """
    if not isinstance(label, str):
        raise ValueError('Band name definition is not a string.')
    if not len(band_definition) == 2:
        raise ValueError('Band limit definition is not the right size.')
    if not band_definition[0] < band_definition[1]:
        raise ValueError('Band limit definitions are invalid.')
