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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 bias_correct(params, data, acf=None):
 """ Calculate and apply a bias correction to the given fit parameters Parameters params : lmfit.Parameters The model parameters. These will be modified. data : 2d-array The data which was used in the fitting acf : 2d-array ACF of the data. Default = None. Returns ------- None See Also -------- :func:`AegeanTools.fitting.RB_bias` """

    bias = RB_bias(data, params, acf=acf)
    i = 0
    for p in params:
        if 'theta' in p:
            continue
        if params[p].vary:
            params[p].value -= bias[i]
            i += 1
    return