Add docstring and change func name

ocf_data_sampler/load/utils.py

@@ -29,7 +29,15 @@ def make_spatial_coords_increasing(ds: xr.Dataset, x_coord: str, y_coord: str) -
     return ds
 
 
-def underlying_array(ds: xr.Dataset, datavar: str | None = None) -> xr.DataArray:
+def get_xr_data_array_from_xr_dataset(ds: xr.Dataset, datavar: str | None = None) -> xr.DataArray:
+    """Return underlying xr.DataArray from passed xr.Dataset. If davar provided, returns specified variable. 
+    If datavar not provided, checks only one variable is present and returns it as an xr.DataArray.
+
+    Args:
+        ds: xr.Dataset to extract xr.DataArray from
+        datavar: (if provided) return specific variable from ds
+    """
+
     if datavar:
         return ds[datavar]
     datavars = list(ds.var())