A fake field data container used to calculate dependencies.
Initialize self. See help(type(self)) for accurate signature.
Returns a new dict with keys from iterable and values equal to value.
If key is not found, d is returned if given, otherwise KeyError is raised
2-tuple; but raise KeyError if D is empty.
If E is present and has a .keys() method, then does: for k in E: D[k] = E[k] If E is present and lacks a .keys() method, then does: for k, v in E: D[k] = v In either case, this is followed by: for k in F: D[k] = F[k]
Factory for default value called by __missing__().