code: def color(self, c):
      self._color = c
      self.fshader["isocolor"] = Color(c).rgba
  
imports: from .base_filter import Filter
  from ..shaders import Function, Varying
  from ...color import colormap, Color
label_desc: Use image node_id 7 for calling the IsolineFilter obj's underlying member method code with example usage: obj.color(c) without return types