def METHOD_NAME(self):
    for el, val in self.re.items():
        if not val:
            zero_field_z_faces = [0] * len(self.x)
            self.re[el] = zero_field_z_faces
    for el, val in self.im.items():
        if not val:
            zero_field_z_faces = [0] * len(self.x)
            self.im[el] = zero_field_z_faces