Description
These are the types
X of lists that can be constructed by expressions of the form
X {a,b,c,...}, or, for lists of length one, by an expression of the form
X a. They also act on sequences.
i1 : X = new WrapperType of BasicList
o1 = X
o1 : WrapperType

i2 : X {a,b,c}
o2 = X{a, b, c}
o2 : X

i3 : X a
o3 = X{a}
o3 : X
