How to use the astroquery.utils.commons.parse_coordinates function in astroquery

if action == 'data':
            raise NotImplementedError(
                "The action='data' option is a placeholder for future " +
                "functionality.")

        args = {
            'INTERSECT': intersect
        }

        # Note: in IBE, if 'mcen' argument is present, it is true.
        # If absent, it is false.
        if most_centered:
            args['mcen'] = '1'

        if coordinate is not None:
            c = commons.parse_coordinates(coordinate).transform_to(coord.ICRS)
            args['POS'] = '{0},{1}'.format(c.ra.deg, c.dec.deg)
            if width and height:
                args['SIZE'] = '{0},{1}'.format(
                    coord.Angle(width).value,
                    coord.Angle(height).value)
            elif width or height:
                args['SIZE'] = str(coord.Angle(width or height).value)

        if where:
            args['where'] = where

        if columns:
            if isinstance(columns, six.string_types):
                columns = columns.split()
            args['columns'] = ','.join(columns)

def _validate_coord(coordinates):
    """Validate coordinates and return them as ICRS RA and DEC in deg."""
    if isinstance(coordinates, (list, tuple)) and len(coordinates) == 2:
        icrscoord = ICRS(Longitude(coordinates[0], unit=u.degree),
                         Latitude(coordinates[1], unit=u.degree))
    else:
        c = commons.parse_coordinates(coordinates)
        if isinstance(c, SkyCoord):
            icrscoord = c.transform_to(ICRS).frame
        elif isinstance(c, BaseCoordinateFrame):
            icrscoord = c.transform_to(ICRS)
        else:  # Assume already ICRS
            icrscoord = c

    return icrscoord.ra.degree, icrscoord.dec.degree

about ('ra', 'dec', 'unit') parameters.

        Examples
        --------
        >>> from astroquery.alfalfa import Alfalfa
        >>> from astropy import coordinates as coords
        >>> C = coords.SkyCoord('0h8m05.63s +14d50m23.3s')
        >>> agc = Alfalfa.query_region(C,'3 arcmin')

        Returns
        -------
        result : AGC number for object nearest supplied position.

        """

        coordinates = commons.parse_coordinates(coordinates)

        ra = coordinates.ra.degree
        dec = coordinates.dec.degree
        dr = coord.Angle(radius).deg

        cat = self.get_catalog()

        # Use RA and DEC to find appropriate AGC
        if optical_counterpart:
            ra_ref = cat['RAdeg_OC']
            dec_ref = cat['DECdeg_OC']
        else:
            ra_ref = cat['RAdeg_HI']
            dec_ref = cat['Decdeg_HI']

        dra = np.abs(ra_ref - ra) \

def _args_to_payload(self, *args, **kwargs):
        request_payload = {}

        request_payload['database'] = kwargs.get('database', self.database)

        programme_id = kwargs.get('programme_id', self.programme_id)

        request_payload['programmeID'] = self._verify_programme_id(
            programme_id, query_type=kwargs['query_type'])
        sys = self._parse_system(kwargs.get('system'))
        request_payload['sys'] = sys
        if sys == 'J':
            C = commons.parse_coordinates(args[0]).transform_to(coord.ICRS)
            request_payload['ra'] = C.ra.degree
            request_payload['dec'] = C.dec.degree
        elif sys == 'G':
            C = commons.parse_coordinates(args[0]).transform_to(coord.Galactic)
            request_payload['ra'] = C.l.degree
            request_payload['dec'] = C.b.degree
        return request_payload

request_payload = {}

        request_payload['database'] = kwargs.get('database', self.database)

        programme_id = kwargs.get('programme_id', self.programme_id)

        request_payload['programmeID'] = self._verify_programme_id(
            programme_id, query_type=kwargs['query_type'])
        sys = self._parse_system(kwargs.get('system'))
        request_payload['sys'] = sys
        if sys == 'J':
            C = commons.parse_coordinates(args[0]).transform_to(coord.ICRS)
            request_payload['ra'] = C.ra.degree
            request_payload['dec'] = C.dec.degree
        elif sys == 'G':
            C = commons.parse_coordinates(args[0]).transform_to(coord.Galactic)
            request_payload['ra'] = C.l.degree
            request_payload['dec'] = C.b.degree
        return request_payload

def __getCoordInput(self, value, msg):
        if not (isinstance(value, str) or isinstance(value, commons.CoordClasses)):
            raise ValueError(
                str(msg) + " must be either a string or astropy.coordinates")
        if isinstance(value, str):
            c = commons.parse_coordinates(value)
            return c
        else:
            return value

def _parse_coordinates(coordinates):
    try:
        c = commons.parse_coordinates(coordinates)
        # now c has some subclass of astropy.coordinate
        # get ra, dec and frame
        return _fermi_format_coords(c)
    except (u.UnitsError, TypeError):
        raise Exception("Coordinates not specified correctly")

def handle_coordinates(url, key, coordinates):
    """ Handler function for coordinates """
    assert(key == "coordinates")
    coordinates = commons.parse_coordinates(coordinates)
    if coordinates is not None:
        return "%s/ra=%f/dec=%f" % (url, coordinates.ra.deg, coordinates.dec.deg)
    return url