def getVersion(self, agent, word):
        """
        => version string /None
        """
        version_markers = self.version_markers if \
            isinstance(self.version_markers[0], (list, tuple)) else [self.version_markers]
        version_part = agent.split(word, 1)[-1]
        for start, end in version_markers:
            if version_part.startswith(start) and end in version_part:
                version = version_part[1:]
                if end:  # end could be empty string
                    version = version.split(end)[0]
                if not self.allow_space_in_version:
                    version = version.split()[0]
                return version
=> version string /None