### Check fixedpoint works for simulation time
>>> from topo.misc import fixedpoint
>>> import topo
>>> original_type = topo.sim.time_type
>>> original_args = topo.sim.time_type_args
>>> topo.sim.initialized=False
>>> topo.sim.time_type = fixedpoint.FixedPoint
>>> topo.sim.time_type_args = (4,)
>>> z = fixedpoint.FixedPoint(0.999,4)
>>> z-=topo.sim.convert_to_time_type(0.0004)
>>> z
FixedPoint('0.9986', 4)
>>> topo.sim.time_type = original_type
>>> topo.sim.time_type_args = original_args
>>> topo.sim.intialized=True



