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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 __system_methodHelp(method_name, **kwargs):
 """ Returns the documentation of the given method name. :param method_name: Name of a method available for current entry point (and protocol) :param kwargs: :return: Documentation text for the RPC method """

    entry_point = kwargs.get(ENTRY_POINT_KEY)
    protocol = kwargs.get(PROTOCOL_KEY)

    method = registry.get_method(method_name, entry_point, protocol)
    if method is None:
        raise RPCInvalidParams('Unknown method {}. Unable to retrieve its documentation.'.format(method_name))
    return method.html_doc