and val m1 = mapOf(1 to 1, 2 to 2) val m2 ...

# stdlib

[marcinmoskala]

and
val m1 = mapOf(1 to 1, 2 to 2)
val m2 = mapOf(2 to 1, 3 to 2)
assertEquals(m1 + m2, mapOf(1 to 1, 2 to 3, 3 to 2))