Merges the key/value pairs from the map m2 into map m1 and returns the result as a new map.
Note that keys in m1 that match keys in m2 will be over-written with the value in m2.
- Returns:
m - A map containing all keys in both m1 and m2
- Arguments:
m1 - The starting map.
m2 - A map that will be added to m1.