@property
    def wavelength(self):
        return c/(self._frequency*self._n)
Returns True if the key is in the cache and has not expired.
dataset/ETHPy150Open sympy/sympy/sympy/physics/optics/waves.py/TWave.wavelength--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/core/cache/backends/base.py/BaseCache.has_key