getKEGGnodeData: Get or set list of KEGG node or edge data
Description
The 'get' methods extracts KEGG node (edge) attributes from a graph produced
by calling parseKGML2Graph or
KEGGpathway2Graph. The 'set' methods writes a list into
the edge or node data.
Node and edge data is stored as list within environments in graphs to save
memory and speed up graph manipulations. When using
getKEGGnodeData or getKEGGedgeData is called, the list
is extracted out of the environment and returned.