<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def delta_E( self ):
 """ The change in system energy if this jump were accepted. Args: None Returns: (Float):
 delta E """

        site_delta_E = self.final_site.energy - self.initial_site.energy
        if self.nearest_neighbour_energy:
            site_delta_E += self.nearest_neighbour_delta_E()
        if self.coordination_number_energy:
            site_delta_E += self.coordination_number_delta_E()
        return site_delta_E