Access fields of Named Tuple

---

examples/tuples/named_tuple_fields.cr

tpl = {fname: "Foo", "lname": "Bar"}
puts tpl
puts typeof(tpl)

puts tpl[:fname]
puts tpl["fname"]
puts tpl[:lname]
puts tpl["lname"]

# tpl["fname"] = "Jane"
# tpl["lname"] = "Bar"