readBlockTemporaries
[ tokenType = $: ]
whileTrue: [ self currentChar isAlphabetic
ifFalse: [ self error: 'ill formed block argument'].
self nextLex.
self tokenIsName
ifTrue: [ self addTempName: token ]
ifFalse: [ self error: 'invalid block argument list '].
self nextLex ].
tokenType = $|
ifTrue: [ self nextLex ]
ifFalse: [ self error: 'invalid block argument list ']