def freq_wavelength( **kw ):
"""A kind of **Solver** for frequency-wavelength problems in Standard units
of meters and Hertz.
:param f: Frequency in Hz
:param l: Wavelength in m
:returns: dict with both values
"""
c= 299792.458
args= AttrDict( kw )
if 'f' in args:
args.l= 1000*c/args.f
elif 'l' in args:
args.f = c/(args.l/1000)
else:
raise NoSolutionError( "Insufficient Data: {0!r}".format(args) )
return args
