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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 _convert_size(self, size_str):
 """Convert units to GB"""

        suffix = size_str[-1]
        if suffix == 'K':
            multiplier = 1.0 / (1024.0 * 1024.0)
        elif suffix == 'M':
            multiplier = 1.0 / 1024.0
        elif suffix == 'T':
            multiplier = 1024.0
        else:
            multiplier = 1

        try:
            val = float(size_str.split(' ')[0])
            return val * multiplier
        except ValueError:
            return 0.0