| cm matcher answerNode methodNode rewriteRule replacement |

cm := FooClass >> #foo:.
methodNode := RBParser parseMethod: cm sourceCode.
replacement := '`@collection collect: `@arg1
							thenDo: [ : fileEntry |
								index := index + 1.
								JobProgress progress: (0.1 * index); title: ''Procesing...'', index asString ]'.
matcher := RBParseTreeSearcher new
	matches: '`@collection collect: `@arg1'
	do: [ :aNode :answer | answer isNil ifTrue: [ aNode ] ifFalse: [ answer ] ].
answerNode := matcher executeTree: methodNode.

rewriteRule := RBParseTreeRewriter new.
(rewriteRule replace: answerNode newSource with: replacement) executeTree: cm parseTree