Creates a key-value map using the given f
function to determine the key
and the given m
function to attempt to merge any duplicates.
Creates a key-value map using the given f
function to determine the key
and the given m
function to attempt to merge any duplicates.
If m
returns None an exception is thrown.
the type of key of the map
the function that determines the key
the merging function
a key-value map from the original collection