def get_heteroatoms(self, elements=None):
        """
        Identify non-H, non-C atoms in the MoleculeGraph, returning a list of
        their node indices.

        :param elements: List of elements to identify (if only certain
            functional groups are of interest).
        :return: set of ints representing node indices
        """

        heteroatoms = set()

        for node in self.molgraph.graph.nodes():
            if elements is not None:
                if str(self.species[node]) in elements:
                    heteroatoms.add(node)
            else:
                if str(self.species[node]) not in ["C", "H"]:
                    heteroatoms.add(node)

        return heteroatoms
def get_heteroatoms ( self , elements = None ) : heteroatoms = set ( ) for node in self . molgraph . graph . nodes ( ) : if elements is not None : if str ( self . species [ node ] ) in elements : heteroatoms . add ( node ) else : if str ( self . species [ node ] ) not in [ "C" , "H" ] : heteroatoms . add ( node ) return heteroatoms
Identify non-H, non-C atoms in the MoleculeGraph, returning a list of
        their node indices.

        :param elements: List of elements to identify (if only certain
            functional groups are of interest).
        :return: set of ints representing node indices