def _process_defaults(G, schemas):
    """
    Process dependencies for parameters default values in the order schemas are defined.
    """
    for schema in schemas:
        for name, value in six.iteritems(schema):
            absent = name not in G.nodes
            is_none = G.nodes.get(name, {}).get("value") is None
            immutable = value.get("immutable", False)
            if absent or is_none or immutable:
                _process(G, name, value.get("default"))

    Process dependencies for parameters default values in the order schemas are defined.
    
st2common/st2common/util/param.py