Replace with just f[idx]. Calling QgsFeature.attributes()
allocates a list of all attributes, which is inefficient
when only a single attribute value is needed.
Include descriptive text with the specified parameter value
in error, and always check that sources were loaded to avoid
raw Python exceptions when they are not
This algorithm creates geometries which enclose the features
from an input layer.
Numerous enclosing geometry types are supported, including
bounding boxes (envelopes), oriented rectangles, circles and
convex hulls.
Optionally, the features can be grouped by a field. If set,
this causes the output layer to contain one feature per grouped
value with a minimal geometry covering just the features with
matching values.
