39 Maps

A map maps keys to values.

Maps must be created with make (not new) before use; the nil map is empty and cannot be assigned to.
40 Map literals

It's good!!
41 Map literals continued

If the top-level type is just a type name, you can omit it from the elements of the literal.
:D
42 Mutating Maps

Insert or update an element in map m:
`m[key] = elem`

Retrieve an element:
`elem = m[key]`

Delete an element:
`delete(m, key)`

Test that a key is present with a two-value assignment:
`elem, ok = m[key]`
If key is in m, ok is true. If not, ok is false and elem is the zero value for the map's element type.

Similarly, when reading from a map if the key is not present the result is the zero value for the map's element type.
43 Exercise: Maps
43 Exercise: Maps - passed all test suites!!
44 Function values
45 Function closures
46 Exercise: Fibonacci closure
46 Exercise: Fibonacci closure - implemented