Convert coordinate string to `~astropy.coordinates.Angle` or `~astropy.units.quantity.Quantity` objects

def convert_coordinates(self):
        """
        Convert coordinate string to `~astropy.coordinates.Angle` or `~astropy.units.quantity.Quantity` objects
        """
        coord_list_str = regex_coordinate.findall(self.reg_str) + regex_length.findall(self.reg_str)
        coord_list = []

        if self.region_type == 'poly':
            if len(coord_list_str) < 4:
                self._raise_error('Not in proper format: {} polygon should have > 4 coordinates'.format(self.reg_str))
            if coord_list_str[0] != coord_list_str[-1]:
                self._raise_error("Not in proper format: '{0}', "
                                  "In polygon, the last and first coordinates should be same".format(self.reg_str))
        else:
            if len(coord_list_str) != len(self.language_spec[self.region_type]):
                self._raise_error("Not in proper format: '{0}', "
                                  "Does not contain expected number of parameters for the region '{1}'"
                                  .format(self.reg_str, self.region_type))

        for attr_spec, val_str in zip(self.language_spec[self.region_type], coord_list_str):

            if attr_spec == 'c':
                if len(val_str) == 2 and val_str[1] != '':
                    coord_list.append(CoordinateParser.parse_coordinate(val_str[0]))
                    coord_list.append(CoordinateParser.parse_coordinate(val_str[1]))
                else:
                    self._raise_error("Not in proper format: {0} should be a coordinate".format(val_str))
            if attr_spec == 'pl':
                if len(val_str) == 2 and val_str[1] != '':
                    coord_list.append(CoordinateParser.parse_angular_length_quantity(val_str[0]))
                    coord_list.append(CoordinateParser.parse_angular_length_quantity(val_str[1]))
                else:
                    self._raise_error("Not in proper format: {0} should be a pair of length".format(val_str))
            if attr_spec == 'l':
                if isinstance(val_str, six.string_types):
                    coord_list.append(CoordinateParser.parse_angular_length_quantity(val_str))
                else:
                    self._raise_error("Not in proper format: {0} should be a single length".format(val_str))
            if attr_spec == 's':
                if self.region_type == 'symbol':
                    if val_str in valid_symbols:
                        self.meta['symbol'] = val_str
                    else:
                        self._raise_error("Not in proper format: '{0}' should be a symbol".format(val_str))
                elif self.region_type == 'text':
                    self.meta['text'] = val_str[1:-1]

        self.coord = coord_list