// Struct fields are private and immutable by default (making structs immutable as well).
// Their access modifiers can be changed with pub and mut.
// In total, there are 5 possible options:
struct Foo {
a int // private immutable (default)
mut:
b int // private mutable
c int // (you can list multiple fields with the same access modifier)
pub:
d int // public immmutable (readonly)
pub mut:
e int // public, but mutable only in parent module
__global:
f int // public and mutable both inside and outside parent module
} // (not recommended to use, that's why the 'global' keyword
// starts with __)