<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _pad(input_signal, length, average=10):
 """ Helper function which increases the length of an input signal. The original is inserted at the centre of the new signal and the extra values are set to the average of the first and last parts of the original, respectively. :param input_signal: the signal to be padded :param length: the length of the padded signal :param average: the number of points at the beginning/end of the signal which are averaged to calculate the padded value :return: """

    padded_input_signal = numpy.zeros(length, input_signal.dtype)
    start_offset = int((len(padded_input_signal) - len(input_signal)) / 2)
    padded_input_signal[:start_offset] = numpy.average(input_signal[0:average])
    padded_input_signal[start_offset:(start_offset + len(input_signal))] = input_signal[:]
    padded_input_signal[(start_offset + len(input_signal)):] = numpy.average(input_signal[-average:])
    return padded_input_signal