Search for query, type_ is optional.
    type_: 'User', 'Startup', 'MarketTag', 'LocationTag'

def get_search(self, query, type_=None):
    """Search for query, type_ is optional.
    type_: 'User', 'Startup', 'MarketTag', 'LocationTag'
    """
    search_url = _S_SEARCH.format(c_api=_C_API_BEGINNING,
                                  api=_API_VERSION,
                                  query=_format_query(query),
                                  at=self.access_token)
    if type_ is not None:
      search_url + _TYPE_SUFFIX.format(type_=type_)
    return _get_request(search_url)