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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 checkAvailable(from_module):
 """Call me at checkConfig time to properly report config error if neither txrequests or treq is installed """

        if txrequests is None and treq is None:
            config.error("neither txrequests nor treq is installed, but {} is requiring it\n\n{}".format(
                from_module, HTTPClientService.TREQ_PROS_AND_CONS))