Nonzero dipole matrix element for forbidden transitions

[EvgAnikin]

For a dipole-forbidden transition in $\mathrm{Ca}^+$ ion (and I guess, for many other Atoms), the matrix_element attribute is unexpectedly nonzero:

>>> Ca_plus = Atom('Ca+')
>>> Ca_plus('4S1/2').to('3D5/2').matrix_element.to('e a0').m
0.0012221264747753456

I guess that the problem originates from the fact that the code doesn't try to distinguish between dipole-allowed and dipole-forbidden transitions. It and always calculates matrix element from lifetime using the dipole formula, whereas it is not valid for quadrupole and higher-order transitions.