docs: def setValue(self, prop, value, unit=None):
          """Set the value of feature with that name."""
  
          if isinstance(value, int) or isinstance(value, float):
              if prop in self.props:
                  for i, j in [(0, 1), (1, 0)]:
                      if self.props[prop][i] is None:
                          self.props[prop] = (self.props[prop][j], self.props[prop][j])
                  for v in self.props[prop]:
                      v.value, v.unit = value, unit
              else:
                  f = Feature(prop, "=", value, unit=unit)
                  self.props[prop] = (f, f)
          elif prop in self.props:
              self.props[prop].value, self.props[prop].unit = value, unit
          else:
              self.props[prop] = Feature(prop, "=", value, unit=unit)