code: def _get_spec_value(self, form, uid, key, default=''):
          
          if not form or not uid:
              return default
          values = form.get(key, None)
          if not values or len(values) == 0:
              return default
          value = values[0].get(uid, default)
          return api.is_floatable(value) and value or default
docs: Returns the value assigned to the passed in key for the analysis
          service uid from the passed in form.
  
          If check_floatable is true, will return the passed in default if the
          obtained value is not floatable
          :param form: form being submitted
          :param uid: uid of the Analysis Service the specification relates
          :param key: id of the specs param to get (e.g. 'min')
          :param check_floatable: check if the value is floatable
          :param default: fallback value that will be returned by default
          :type default: str, None