human
Complete the below
def _add_msgs_depends(rospack, spec, deps, package_context):

    ''''Add the list of message types that spec depends on to depends.
    @param spec: message to compute dependencies for
    @type  spec: roslib.msgs.MsgSpec/roslib.srvs.SrvSpec
    @param deps [str]: list of dependencies. This list will be updated
    with the dependencies of spec when the method completes
    @type  deps: [str]
    @raise KeyError for invalid dependent types due to missing package dependencies.'
    '''
 ... Can you provide a Python code to compute dependencies for?
assistant
#Here is Python code to compute dependencies for
.
    def _get_valid_packages(package_context, rospack):
        valid_packages = ['', package_context]
        try:
            valid_packages = (valid_packages + rospack.get_depends(package_context, implicit=True))
        except rospkg.ResourceNotFound:
            pass
        return valid_packages
    valid_packages = None
    for t in spec.types:
        t = roslib.msgs.base_msg_type(t)
        if (not roslib.msgs.is_builtin(t)):
            (t_package, t_base) = roslib.names.package_resource_name(t)
            if (t == roslib.msgs.HEADER):
                deps.append(_header_type_name)
            if roslib.msgs.is_registered(t):
                depspec = roslib.msgs.get_registered(t)
                if (t != roslib.msgs.HEADER):
                    if ('/' in t):
                        deps.append(t)
                    else:
                        deps.append(((package_context + '/') + t))
            else:
                if (valid_packages is None):
                    valid_packages = _get_valid_packages(package_context, rospack)
                if (t_package in valid_packages):
                    (key, depspec) = roslib.msgs.load_by_type(t, package_context)
                    if (t != roslib.msgs.HEADER):
                        deps.append(key)
                    roslib.msgs.register(key, depspec)
                else:
                    raise KeyError(t)
            _add_msgs_depends(rospack, depspec, deps, package_context)