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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 find_variable_start_frequency(approximant, parameters, f_start, max_length, delta_f = 1):
 """ Find a frequency value above the starting frequency that results in a waveform shorter than max_length. """

    l = max_length + 1
    f = f_start - delta_f
    while l > max_length:
        f += delta_f
        l = pycbc.waveform.get_waveform_filter_length_in_time(approximant,
                                                      parameters, f_lower=f)
    return f