BF + PEP8: use the `warn` function. A bit of whitespace.
BF + PEP8: use the `warn` function. A bit of whitespace.

matthieudumont/dipy,matthieudumont/dipy,StongeEtienne/dipy,sinkpoint/dipy,villalonreina/dipy,JohnGriffiths/dipy,FrancoisRheaultUS/dipy,villalonreina/dipy,sinkpoint/dipy,JohnGriffiths/dipy,nilgoyyou/dipy,StongeEtienne/dipy,demianw/dipy,nilgoyyou/dipy,demianw/dipy,FrancoisRheaultUS/dipy