Gets the executable corresponding to the specified full name.

        :arg fullname: a string with modulename.executable.

def get_executable(self, fullname):
        """Gets the executable corresponding to the specified full name.

        :arg fullname: a string with modulename.executable.
        """
        result = None
        modname, exname = fullname.split(".")
        module = self.get(modname)
        if module is not None:
            if exname in module.executables:
                result = module.executables[exname]

        return result