def normalize_scope(scope, sep=' ')
      unless (scope.is_a?(String) || scope.is_a?(Array))
        raise ArgumentError.new("Expected scope of type String or Array but was: #{scope.class.name}")
      end
      (scope.is_a?(Array) && scope.join(sep)) || scope
    end
def normalize_scope(scope, sep=' ')
      unless (scope.is_a?(String) || scope.is_a?(Array))
        raise ArgumentError.new("Expected scope of type String or Array but was: #{scope.class.name}")
      end
      (scope.is_a?(Array) && scope.join(sep)) || scope
    end
Token scope definitions vary by service e.g Google uses space delimited scopes,
 while Github uses comma seperated scopes. This method allows us to normalize
 the token scopes

 @see http://developer.github.com/v3/oauth/#scopes, https://developers.google.com/accounts/docs/OAuth2WebServer#formingtheurl