This function retrieves a tagged or untagged snippet.

def unsnip(tag=None,start=-1):
    """ This function retrieves a tagged or untagged snippet. """
    import IPython
    i = IPython.get_ipython()
    if tag in _tagged_inputs.keys():
        if len(_tagged_inputs[tag]) > 0:
            i.set_next_input(_tagged_inputs[tag][start])
    else:
        if len(_last_inputs) > 0:
            i.set_next_input(_last_inputs[start])