code: def to_params(self):
          
          params = {}
          for name in self.PROPERTIES:
              attr = '_{0}'.format(name)
              value = getattr(self, attr, None) or getattr(self, name, None)
  
              # skip attribute
              if value is None:
                  continue
  
              if isinstance(value, datetime):
                  params[name] = format_time(value)
              elif isinstance(value, list):
                  params[name] = ','.join(map(str, value))
              elif isinstance(value, bool):
                  params[name] = str(value).lower()
              else:
                  params[name] = value
  
          return params
docs: Generates a Hash of property values for the current object. This helper
          handles all necessary type coercions as it generates its output.