remove list from observation type and docstrings

Author: mj-gomes

litebird_sim/hwp_harmonics/hwp_harmonics.py

@@ -118,7 +118,7 @@ def set_band_params_for_one_detector(
 
 def fill_tod_with_hwp_harmonics(
     hwp: NonIdealHWP,
-    observation: Observation | list[Observation],
+    observation: Observation,
     tod: np.ndarray,
     maps: (
         HealpixMap
@@ -165,20 +165,14 @@ def fill_tod_with_hwp_harmonics(
             on the fly (generated by :func:`lbs.get_pointings` per
             detector), or read from ``observations.pointing_matrix``
             (if present).
-            If ``observations`` is not a list, ``pointings`` must be a
-            np.array of shape ``(N_det, N_samples, 3)``. If ``observations``
-            is a list, ``pointings`` must be a list of same length.
+            ``pointings`` must be a np.array of shape ``(N_det, N_samples, 3)``.
 
         hwp_angle (optional) : `2ωt`, hwp rotation angles
             (radians). If ``pointings`` is passed, ``hwp_angle``
             must be passed as well, otherwise both must be
             ``None``. If not passed, it is computed on the fly
             (generated by :func:`lbs.get_pointings` per detector).
-            If ``observations`` is not a list, ``hwp_angle`` must
-            be a np.array of dimensions (N_samples).
-
-            If ``observations`` is a list, ``hwp_angle`` must be a
-            list with the same length.
+            ``hwp_angle`` must be a np.array of dimensions (N_samples).
 
         save_tod (bool) : if True, ``obs.tod`` is saved in
             ``observations.tod`` and locally as a .npy file;