view
let call: <param, return>(_: string) => (_: param) => (_: address) => option<return>
The call call(v, p, a) calls the view v with parameter
param at the contract whose address is a. The value returned
is None() if the view does not exist, or has a different type of
parameter, or if the contract does not exist at that
address. Otherwise, it is Some(v), where v is the return value
of the view. Note: the storage of the view is the same as when the
execution of the contract calling the view started.