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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def enable_pow_mining(chain_class: Type[BaseChain]) -> Type[BaseChain]: """ Inject on demand generation of the proof of work mining seal on newly mined blocks into each of the chain's vms. """

    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)