'Topo object.
Optional named parameters:
hinfo: default host options
sopts: default switch options
lopts: default link options
calls build()'

def __init__(self, *args, **params):

    self.g = MultiGraph()
    self.hopts = params.pop('hopts', {})
    self.sopts = params.pop('sopts', {})
    self.lopts = params.pop('lopts', {})
    self.ports = {}
    self.build(*args, **params)
