Return info about last time fun was called on each minion

    CLI Example:

    .. code-block:: bash

        salt '*' ret.get_fun mysql network.interfaces

def get_fun(returner, fun):
    '''
    Return info about last time fun was called on each minion

    CLI Example:

    .. code-block:: bash

        salt '*' ret.get_fun mysql network.interfaces
    '''
    returners = salt.loader.returners(__opts__, __salt__)
    return returners['{0}.get_fun'.format(returner)](fun)