fix formatting

  >>> # When mixed training is toggled.

  >>> import numpy as np

  >>> from deepchem.trans.transformers import RxnSplitTransformer

  >>> reactions = np.array(

    [

        "CC(C)C[Mg+].CON(C)C(=O)c1ccc(O)nc1>C1CCOC1.[Cl-]>CC(C)CC(=O)c1ccc(O)nc1",

        "CCn1cc(C(=O)O)c(=O)c2cc(F)c(-c3ccc(N)cc3)cc21.O=CO>>CCn1cc(C(=O)O)c(=O)c2cc(F)c(-c3ccc(NC=O)cc3)cc21"

    ],

    dtype=object)

  >>> reactions = np.array(["CC(C)C[Mg+].CON(C)C(=O)c1ccc(O)nc1>C1CCOC1.[Cl-]>CC(C)CC(=O)c1ccc(O)nc1","CCn1cc(C(=O)O)c(=O)c2cc(F)c(-c3ccc(N)cc3)cc21.O=CO>>CCn1cc(C(=O)O)c(=O)c2cc(F)c(-c3ccc(NC=O)cc3)cc21"], dtype=object)

  >>> trans = RxnSplitTransformer(sep_reagent=True)

  >>> split_reactions = trans.transform_array(X=reactions, y=np.array([]), w=np.array([]), ids=np.array([]))

  >>> split_reactions