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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _visibleToRealColumn(self, text, visiblePos):
 """If \t is used, real position of symbol in block and visible position differs This function converts visible to real. Bigger value is returned, if visiblePos is in the middle of \t, None if text is too short """

        if visiblePos == 0:
            return 0
        elif not '\t' in text:
            return visiblePos
        else:
            currentIndex = 1
            for currentVisiblePos in self._visibleCharPositionGenerator(text):
                if currentVisiblePos >= visiblePos:
                    return currentIndex - 1
                currentIndex += 1

            return None