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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 get_backend(alias):
 """ Returns ``Repository`` class identified by the given alias or raises VCSError if alias is not recognized or backend class cannot be imported. """

    if alias not in settings.BACKENDS:
        raise VCSError("Given alias '%s' is not recognized! Allowed aliases:\n"
            "%s" % (alias, pformat(settings.BACKENDS.keys())))
    backend_path = settings.BACKENDS[alias]
    klass = import_class(backend_path)
    return klass