def create_loader(ctx):
loader = Loader()
url_fields = []
for c in ctx:
if c != "id" and (ctx[c] == "@id") or (isinstance(ctx[c], dict) and ctx[c].get("@type") == "@id"):
url_fields.append(c)
loader.url_fields = url_fields
loader.idx["cwl:JsonPointer"] = {}
return loader
