local m = {}
function m:def(source, callback)
self:eachDef(source.loc, callback)
end
function m:ref(source, callback)
self:eachRef(source.loc, callback)
end
function m:field(source, key, callback)
self:eachField(source.loc, key, callback)
end
function m:value(source, callback)
self:eachValue(source.loc, callback)
end
return m