def find_context_bydevL2addr(self, dev_L2addr):
    ' find a context with dev_L2addr. '
    for c in self._db:
        if (c['devL2Addr'] == dev_L2addr):
            return c
        if (c['devL2Addr'] == '*'):
            return c
    return None
find a context with dev_L2addr.
def find_context_bydevL2addr(self, dev_L2addr):
    '  '
    for c in self._db:
        if (c['devL2Addr'] == dev_L2addr):
            return c
        if (c['devL2Addr'] == '*'):
            return c
    return None