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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 load_backend(backend_name):
 """ load pool backend."""

    try:
        if len(backend_name.split(".")) > 1:
            mod = import_module(backend_name)
        else:
            mod = import_module("spamc.backend_%s" % backend_name)
        return mod
    except ImportError:
        error_msg = "%s isn't a spamc backend" % backend_name
        raise ImportError(error_msg)