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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def slice_vec(expr, start, stop):
 """ Slices the vector. Args: expr (WeldObject) start (Long) stop (Long) """

    weld_obj = WeldObject(encoder_, decoder_)

    expr_var = weld_obj.update(expr)
    if isinstance(expr, WeldObject):
        expr_var = expr.obj_id
        weld_obj.dependencies[expr_var] = expr

    weld_template = """
    slice(%(expr)s, %(start)sL, %(stop)sL)
    """
    weld_obj.weld_code = weld_template % {"expr":expr_var,
                                          "start":start,
                                          "stop":stop}
    return weld_obj