Hello, I have to make some code that convert a binary to a decimal and im not allowed to use the convert methods that Pharo has. So I have written this : decimalFromBinary: aString    | result isValid |    isValid = self isValidBinary: aString.    isValid       ifTrue: [ result := 0.          aString reverse             withIndexDo:                [ :digit :index | result := result + (digit digitValue * (2 raisedTo: index - 1)) ].          ^ result ]       ifFalse: [ ^ nil ] isValidBinary: aString    ^ aString allSatisfy: [ :c | c = 0 or: [ c = 1 ] ] but on the first method I see a message that the temp variables are read before written. and the second one I see a message that I use a or instead of searching literals. Where did I think wrong here ? Roelof