code: def enable_pow_mining(chain_class: Type[BaseChain]) -> Type[BaseChain]:
      
      if not chain_class.vm_configuration:
          raise ValidationError("Chain class has no vm_configuration")
  
      vm_configuration = _mix_in_pow_mining(chain_class.vm_configuration)
      return chain_class.configure(vm_configuration=vm_configuration)
docs: Inject on demand generation of the proof of work mining seal on newly
      mined blocks into each of the chain's vms.