Parse type-specific keywords from the metadata: Theme or Place

def _parse_keywords(self, prop):
        """ Parse type-specific keywords from the metadata: Theme or Place """

        keywords = []

        if prop in KEYWORD_PROPS:
            xpath_root = self._data_map['_keywords_root']
            xpath_map = self._data_structures[prop]

            xtype = xpath_map['keyword_type']
            xpath = xpath_map['keyword']
            ktype = KEYWORD_TYPES[prop]

            for element in get_elements(self._xml_tree, xpath_root):
                if get_element_text(element, xtype).lower() == ktype.lower():
                    keywords.extend(get_elements_text(element, xpath))

        return keywords