'Get an HTTP request header.
@type key: C{bytes}
@param key: The name of the header to get the value of.
@rtype: C{bytes} or L{None}
@return: The value of the specified header, or L{None} if that header
was not present in the request.'

def getHeader(self, key):

    value = self.requestHeaders.getRawHeaders(key)
    if (value is not None):
        return value[(-1)]
