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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 functions(start=None, end=None):
 """Get all functions in range. Args: start: Start address of the range. Defaults to IDB start. end: End address of the range. Defaults to IDB end. Returns: This is a generator that iterates over all the functions in the IDB. """

    start, end = fix_addresses(start, end)

    for func_t in idautils.Functions(start, end):
        yield Function(func_t)