untyped is to embed an untyped AST in an typed AST. The embeded untyped AST will be kept as is when the typed one is untyped.
ignore e creates
Pervasives.ignore <e>. No check of
Pervasives is the really OCaml stdlib's
Override expression's type environment field
None of the given content type. If
ty is omitted the container type is
None is not accessible in the environment.
Some e of the given expression. Raises
Some is not accessible in the environment.
Build the list of given expressions. The container type is
t list where
t is the type of the first expression. If no type is given,
Dummy.type_expr is used.
Assert_failure when either
 is not accessible in the environment.