def default_weight(element):
if element in (Atom.N, Atom.O, Atom.P):<EOL><INDENT>return <NUM_LIT><EOL><DEDENT>elif isinstance(element, Radical):<EOL><INDENT>return <NUM_LIT><EOL><DEDENT>return <NUM_LIT:1.0><EOL>
Return weight of formula element.

    This implements the default weight proposed for MapMaker.