How to use the pydruid.utils.having.Having function in pydruid

>>> string_to_num(10.1)
    10.1
    >>> string_to_num('this is not a string') is None
    True
    """
    if isinstance(s, (int, float)):
        return s
    if s.isdigit():
        return int(s)
    try:
        return float(s)
    except ValueError:
        return None


class DimSelector(Having):
    def __init__(self, **args):
        # Just a hack to prevent any exceptions
        Having.__init__(self, type='equalTo', aggregation=None, value=None)

        self.having = {
            'having': {
                'type': 'dimSelector',
                'dimension': args['dimension'],
                'value': args['value'],
            },
        }


def list_minus(l, minus):
    """Returns l without what is in minus

db = caravel.db
    config = caravel.app.config
    DB = caravel.models.Database
    logging.info("Creating database reference")
    dbobj = db.session.query(DB).filter_by(database_name='main').first()
    if not dbobj:
        dbobj = DB(database_name="main")
    logging.info(config.get("SQLALCHEMY_DATABASE_URI"))
    dbobj.set_sqlalchemy_uri(config.get("SQLALCHEMY_DATABASE_URI"))
    dbobj.expose_in_sqllab = True
    db.session.add(dbobj)
    db.session.commit()
    return dbobj


class DimSelector(Having):
    def __init__(self, **args):
        # Just a hack to prevent any exceptions
        Having.__init__(self, type='equalTo', aggregation=None, value=None)

        self.having = {'having': {
            'type': 'dimSelector',
            'dimension': args['dimension'],
            'value': args['value'],
        }}


def list_minus(l, minus):
    """Returns l without what is in minus

    >>> list_minus([1, 2, 3], [2])
    [1, 3]

except ImportError:
    pass


logging.getLogger("MARKDOWN").setLevel(logging.INFO)

DTTM_ALIAS = "__timestamp"
ADHOC_METRIC_EXPRESSION_TYPES = {"SIMPLE": "SIMPLE", "SQL": "SQL"}

JS_MAX_INTEGER = 9007199254740991  # Largest int Java Script can handle 2^53-1

sources = {"chart": 0, "dashboard": 1, "sql_lab": 2}

try:
    # Having might not have been imported.
    class DimSelector(Having):
        def __init__(self, **args):
            # Just a hack to prevent any exceptions
            Having.__init__(self, type="equalTo", aggregation=None, value=None)

            self.having = {
                "having": {
                    "type": "dimSelector",
                    "dimension": args["dimension"],
                    "value": args["value"],
                }
            }


except NameError:
    pass