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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 bend(mapping, source, context=None):
 """ The main bending function. mapping: the map of benders source: a dict to be bent returns a new dict according to the provided map. """

    context = {} if context is None else context
    transport = Transport(source, context)
    return _bend(mapping, transport)