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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 x_runtime(f, *args, **kwargs):
 """X-Runtime Flask Response Decorator."""


    _t0 = now()
    r = f(*args, **kwargs)
    _t1 = now()
    r.headers['X-Runtime'] = '{0}s'.format(Decimal(str(_t1 - _t0)))

    return r