>>> from clc_grade import clc_grade

>>> clc_grade(4.5, 5.0, 5.5, 6.0)
(5.25, 6.0)

>>> clc_grade(3.5, 5.0, 6.5, 4.5)
(5.75, 5.8)

>>> clc_grade(4.5, 5.5, -1.0, 6.0)
(5.0, 6.0)

>>> clc_grade(5.5, -1.0, -1.0, 6.0)
(0.0, 6.0)

>>> clc_grade(-1.0, -1.0, -1.0, 6.0)
(0.0, 0.0)

>>> clc_grade(3.5, 5.0, 6.5, -1.0)
(5.75, 5.8)