'Convert this matrix to Block Sparse Row format.
With copy=False, the data/indices may be shared between this matrix and
the resultant bsr_matrix.
When blocksize=(R, C) is provided, it will be used for construction of
the bsr_matrix.'

def tobsr(self, blocksize=None, copy=False):

    return self.tocsr(copy=False).tobsr(blocksize=blocksize, copy=copy)
