def _test_color_function(self):
        if not callable(self.f):
            raise ValueError("Color function is not callable.")
        try:
            result = self.f(0, 0, 0, 0, 0)
            if len(result) != 3:
                raise ValueError("length should be equal to 3")
        except TypeError as te:
            raise ValueError("Color function needs to accept x,y,z,u,v, "
                             "as arguments even if it doesn't use all of them.")
        except __HOLE__ as ae:
            raise ValueError("Color function needs to return 3-tuple r,g,b.")
        except Exception as ie:
            pass  # color function probably not valid at 0,0,0,0,0
dataset/ETHPy150Open sympy/sympy/sympy/plotting/pygletplot/color_scheme.py/ColorScheme._test_color_function