>>> from ulleres import diametres

>>> du = {
... '52-14':['RB2014','RB2213','RJ2014'],
... '54-14':['RJ2014','RB2514'],
... '52-16':['RJ2514','RB2014'],
... '55-14':['RB2014'],
... }
>>> dr = diametres(du)
>>> dr == {
... '52':['RB2014','RB2213','RJ2014','RJ2514'],
... '54':['RB2514','RJ2014'],
... '55':['RB2014'],
... }
True

>>> du = {
... }
>>> dr = diametres(du)
>>> dr == {
... }
True

>>> du = {
... '52-14':['RB2014','RB2213','RJ2014'],
... '54-14':['RB2514','RJ2014'],
... '52-16':['RB2014','RJ2514'],
... '54-16':['XYZ', 'ABC', 'RB2514','RJ2014'],
... '55-14':['RB2014'],
... '55-16':['RB2014', 'LMN'],
... }
>>> dr = diametres(du)
>>> dr == {
... '52':['RB2014','RB2213','RJ2014','RJ2514'],
... '54':['ABC', 'RB2514','RJ2014', 'XYZ'],
... '55':['LMN', 'RB2014'],
... }
True

>>> du = {
... '52-14':['RB2213','RB2014','RJ2014'],
... '54-14':['RJ2014','RB2514'],
... '55-14':['RB2014'],
... }
>>> dr = diametres(du)
>>> dr == {
... '52':['RB2014','RB2213','RJ2014'],
... '54':['RB2514','RJ2014'],
... '55':['RB2014'],
... }
True