<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def list_types(index_name, host='localhost',port='9200'):
        '''
        Lists the context types available in an index
        '''
        return ElasticSearch(host=host, port=port).type_list(index_name)