Insert parts to an object

Inserts <key, value> pairs to a heap. The keys are determine the ordering of the heap, while the value is the actual value to store.

# S4 method for heap,vector,missing,vector
[(x, i) <- value

Arguments

x	a heap object, such as a fibonacci_heap or a binomial_heap
i	a vector of keys
value	a vector of values for the keys