at:

Return the value in the namespace associated with the key

at:put:

Store the value in the namespace under the key

getDictionary

Return the namespace dictionary

getEvaluationContext

Return a context containing the namespace for evaluating a statement

includesKey:

Return true if the namespace includes the key

removeKey:

Remove the key from the namespace

removeKey:ifAbsent:

Remove the key from the namespace. If the key isn't there, run the code in the fail block.