def fetch_bids_asks(self, symbols=None, params={}):
    self.raise_error(NotSupported, details='API does not allow to fetch all prices at once with a single call to fetch_bids_asks() for now')
def fetch_bids_asks(self, symbols=None, params={}):
    self.raise_error(NotSupported, details='API does not allow to fetch all prices at once with a single call to fetch_bids_asks() for now')