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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 ethinca_order_from_string(order):
 """ Returns the integer giving twice the post-Newtonian order used by the ethinca calculation. Currently valid only for TaylorF2 metric Parameters order : string Returns ------- int """

    if order in get_ethinca_orders().keys():
        return get_ethinca_orders()[order]
    else: raise ValueError("Order "+str(order)+" is not valid for ethinca"
                           "calculation! Valid orders: "+
                           str(get_ethinca_orders().keys()))