TST test more formally _is_1d utility
TST test formaly _check_1d_array
COSMIT remove unecessary ravel
ENH remove unecessary function call
ENH remove _is_1d and _check_1d_array thanks to @GaelVaroquaux
ENH use np.squeeze instead of ravel
flake8
COSMIT + TST quiet test with cath_warning