How to use the pyclipper.CT_DIFFERENCE function in pyclipper

def difference(self, poly):
        # type: (Polygon) -> List[Polygon]
        """Difference from another polygon.

        :param poly: The clip polygon.
        :returns: A list of Polygons representing the difference.

        """
        clipper = self._prepare_clipper(poly)
        if not clipper:
            return []
        differences = clipper.Execute(
            pc.CT_DIFFERENCE, pc.PFT_NONZERO, pc.PFT_NONZERO)

        return self._process(differences)

def diff(subj, clip_paths, subj_closed=True):
    if not subj:
        return []
    if not clip_paths:
        return subj
    pc = pyclipper.Pyclipper()
    if subj:
        subj = pyclipper.scale_to_clipper(subj, SCALING_FACTOR)
        pc.AddPaths(subj, pyclipper.PT_SUBJECT, subj_closed)
    if clip_paths:
        clip_paths = pyclipper.scale_to_clipper(clip_paths, SCALING_FACTOR)
        pc.AddPaths(clip_paths, pyclipper.PT_CLIP, True)
    outpaths = pc.Execute(pyclipper.CT_DIFFERENCE, pyclipper.PFT_EVENODD, pyclipper.PFT_EVENODD)
    outpaths = pyclipper.scale_from_clipper(outpaths, SCALING_FACTOR)
    return outpaths

"""
General Suggestions:
- Contours should only be sent here if they actually overlap.
  This can be checked easily using contour bounds.
- Only perform operations on closed contours.
- contours must have an on curve point
- some kind of a log
"""


_operationMap = {
    "union": pyclipper.CT_UNION,
    "intersection": pyclipper.CT_INTERSECTION,
    "difference": pyclipper.CT_DIFFERENCE,
    "xor": pyclipper.CT_XOR,
}

_fillTypeMap = {
    "evenOdd": pyclipper.PFT_EVENODD,
    "nonZero": pyclipper.PFT_NONZERO,
    # we keep the misspelling for compatibility with earlier versions
    "noneZero": pyclipper.PFT_NONZERO,
}


def clipExecute(subjectContours, clipContours, operation, subjectFillType="nonZero",
                clipFillType="nonZero"):
    pc = pyclipper.Pyclipper()

    for i, subjectContour in enumerate(subjectContours):

if priocode == "RS5":
                        if pyclipper.PointInPolygon(pyclipper.scale_to_clipper((apeast[i],apnorth[i])),VO):
                            asas.ap_free[i] = False

                # Execute clipper command
                FRV = pyclipper.scale_from_clipper(pc.Execute(pyclipper.CT_INTERSECTION, pyclipper.PFT_NONZERO, pyclipper.PFT_NONZERO))

                ARV = pc.Execute(pyclipper.CT_DIFFERENCE, pyclipper.PFT_NONZERO, pyclipper.PFT_NONZERO)

                if not priocode == "RS1" and not priocode == "RS5" and not priocode == "RS7" and not priocode == "RS8":
                    # Make another clipper object for extra intersections
                    pc2 = pyclipper.Pyclipper()
                    # When using RotA clip with pc_rota
                    if priocode == "RS6":
                        # Calculate ARV for RotA
                        ARV_rota = pc_rota.Execute(pyclipper.CT_DIFFERENCE, pyclipper.PFT_NONZERO, pyclipper.PFT_NONZERO)
                        if len(ARV_rota) > 0:
                            pc2.AddPaths(ARV_rota, pyclipper.PT_CLIP, True)
                    else:
                        # Put the ARV in there, make sure it's not empty
                        if len(ARV) > 0:
                            pc2.AddPaths(ARV, pyclipper.PT_CLIP, True)

                # Scale back
                ARV = pyclipper.scale_from_clipper(ARV)

                # Check if ARV or FRV is empty
                if len(ARV) == 0:
                    # No aircraft in the vicinity
                    # Map them into the format ARV wants. Outercircle CCW, innercircle CW
                    ARV_loc[i] = []
                    FRV_loc[i] = circle_lst

pc_rota.AddPath(VO, pyclipper.PT_CLIP, True)
                        elif brg_other[j] <= -110. or brg_other[j] >= 110.:
                            # In overtaking position
                            pc_rota.AddPath(VO, pyclipper.PT_CLIP, True)
                    # Detect conflicts for smaller layer in RS7 and RS8
                    if priocode == "RS7" or priocode == "RS8":
                        if pyclipper.PointInPolygon(pyclipper.scale_to_clipper((gseast[i],gsnorth[i])),VO):
                            asas.inconf2[i] = True
                    if priocode == "RS5":
                        if pyclipper.PointInPolygon(pyclipper.scale_to_clipper((apeast[i],apnorth[i])),VO):
                            asas.ap_free[i] = False

                # Execute clipper command
                FRV = pyclipper.scale_from_clipper(pc.Execute(pyclipper.CT_INTERSECTION, pyclipper.PFT_NONZERO, pyclipper.PFT_NONZERO))

                ARV = pc.Execute(pyclipper.CT_DIFFERENCE, pyclipper.PFT_NONZERO, pyclipper.PFT_NONZERO)

                if not priocode == "RS1" and not priocode == "RS5" and not priocode == "RS7" and not priocode == "RS8":
                    # Make another clipper object for extra intersections
                    pc2 = pyclipper.Pyclipper()
                    # When using RotA clip with pc_rota
                    if priocode == "RS6":
                        # Calculate ARV for RotA
                        ARV_rota = pc_rota.Execute(pyclipper.CT_DIFFERENCE, pyclipper.PFT_NONZERO, pyclipper.PFT_NONZERO)
                        if len(ARV_rota) > 0:
                            pc2.AddPaths(ARV_rota, pyclipper.PT_CLIP, True)
                    else:
                        # Put the ARV in there, make sure it's not empty
                        if len(ARV) > 0:
                            pc2.AddPaths(ARV, pyclipper.PT_CLIP, True)

                # Scale back