TypeExpr
Supertype of the forms a type takes.
A form is a child of whatever refers to it: a Type, a
Binder, or an enclosing form. Its span includes any
parentheses around it, since parentheses that only group a type are not a
form of their own. Type forms, arguments, and items declare nothing. Only a
union member written after a | carries a doc, from the comment block above
that |.
Inherits from: Node