Writes a Feature object as GML.
ver specifies the gml version to encode. Supported versions include 2, 3, and 3.2.
format specifies whether to format or pretty print the result.
bounds specifies whether to include feature bounds in the result.
xmldecl specifies whether to include the XML declaration in the result.
nsprefix specifies the prefix to be mapped to the namespace uri for the feature schema.