list.keys

List of keys from a list of key-value pairs

list.lookup

lookup a l is the first value in l corresponding to the key a, or none if no such element exists.

list.lookup_all

lookup_all a l is the list of all values in l corresponding to the key a.

list.kerase

Remove the first pair with the key a.

list.kinsert

Insert the pair ⟨a, b⟩ and erase the first pair with the key a.

list.kunion

kunion l₁ l₂ is the append to l₁ of l₂ after, for each key in l₁, the first matching pair in l₂ is erased.