code: def __call__(self, r, g, b):
      c = self._interpolate_axis
      return c(0, r), c(1, g), c(2, b)
  
imports: from sympy.core.basic import Basic
  from sympy.core.symbol import Symbol, symbols
  from sympy.utilities.lambdify import lambdify
  from .util import interpolate, rinterpolate, create_bounds, update_bounds
  from sympy.utilities.iterables import sift
label_desc: Use image node_id 5 for calling the ColorGradient obj's underlying member method code with example usage: obj.__call__(r, g, b) and returns: c,  c,  c