SWI-Prolog -- Send methods

chain_table ->add: key=any, value=any: Add association to table if this association is not already part of the table. See also chain_table->append.
chain_table ->append: key=any, value=any: Append association to the table. If this is a new key, associate a new chain holding the value with this key. Otherwise append the value to the chain associated to key. See also chain_table->add.
chain_table ->delete: key=any, value=[any]: Delete all associations with the given key. If value is specified, the first occurrence is deleted from the associated chain. If the chain then becomes empty the entire association is deleted.
Fails is key is not in the table, or a value is specified and not in the table.
chain_table ->prepend: key=any, value=any: As chain_table->append but, if there is already a chain associated to key, the value is added to the start of the chain rather than to the end.