class InvalidUserError < StandardError
end
+# Domain is syntactically invalid.
+class InvalidDomainError < StandardError
+end
+
# Used to indicate that an user does not exist.
class NonexistentUserError < StandardError
end
-
# Used to indicate that a domain does not exist.
class NonexistentDomainError < StandardError
end
+
+
+# When you try to rename a user on top of one that already exists.
+class UserAlreadyExistsError < StandardError
+end