from qsiprep.workflows.dwi.fsl import init_fsl_hmc_wf
wf = init_fsl_hmc_wf({'dwi_series': [
                      '.../opposite/sub-1/dwi/sub-1_dir-AP_dwi.nii.gz'],
                     'dwi_series_pedir': 'j',
                     'fieldmap_info': {'suffix': 'rpe_series',
                      'rpe_series': ['.../opposite/sub-1/dwi/sub-1_dir-PA_dwi.nii.gz']},
                     'concatenated_bids_name': 'sub-1'},
                     b0_threshold=100,
                     impute_slice_threshold=0.,
                     fmap_demean=False,
                     fmap_bspline=False,
                     eddy_config=None,
                     source_file='/path/to/dwi/sub-X_dwi.nii.gz',
                     omp_nthreads=1)