setLinkState(string, string, int, string) -> None
        Sets the state for the given tls and link index. The state must be one
        of rRgGyYoOu for red, red-yellow, green, yellow, off, where lower case letters mean that the stream has to decelerate.
        The link index is shown the gui when setting the appropriate junctino
        visualization optin.

def setLinkState(self, tlsID, tlsLinkIndex, state):
        """setLinkState(string, string, int, string) -> None
        Sets the state for the given tls and link index. The state must be one
        of rRgGyYoOu for red, red-yellow, green, yellow, off, where lower case letters mean that the stream has to decelerate.
        The link index is shown the gui when setting the appropriate junctino
        visualization optin.
        """
        fullState = list(self.getRedYellowGreenState(tlsID))
        if tlsLinkIndex >= len(fullState):
            raise TraCIException(None, None, "Invalid tlsLinkIndex %s for tls '%s' with maximum index %s." % (
                tlsLinkIndex, tlsID, len(fullState) - 1))
        else:
            fullState[tlsLinkIndex] = state
            self.setRedYellowGreenState(tlsID, ''.join(fullState))