def METHOD_NAME(size, srcUnit, dstUnit):
    """Converts a number from a given source unit to a destination unit.
    Example:
      In [1]: convertSizeUnits(1024, 'B', 'kB')
      Out[1]: 1
      In [2]: convertSizeUnits(1024, 'MB', 'kB')
      Out[2]: 1048576
    :param size: number to convert
    :param srcUnit: unit of the number. Any of ( 'B', 'kB', 'MB', 'GB', 'TB', 'PB')
    :param dstUnit: unit expected for the return. Any of ( 'B', 'kB', 'MB', 'GB', 'TB', 'PB')
    :returns: the size number converted in the dstUnit. In case of problem -sys.maxint is returned (negative)
    """
    srcUnit = srcUnit.upper()
    dstUnit = dstUnit.upper()
    try:
        convertedValue = float(size) * SIZE_UNIT_CONVERSION[srcUnit] / SIZE_UNIT_CONVERSION[dstUnit]
        return convertedValue
    # TypeError, ValueError: size is not a number
    # KeyError: srcUnit or dstUnit are not in the conversion list
    except (TypeError, ValueError, KeyError):
        return -sys.maxsize