code: def getMajorMinor(deviceName, dmsetupLs):
      
  
      startingIndex = string.rindex(dmsetupLs, deviceName) + len(deviceName)
      endingIndex = string.index(dmsetupLs[startingIndex:], "\n") + startingIndex
      # trim the preceding tab and ()'s
      newStr = dmsetupLs[startingIndex + 2: endingIndex - 1]
      return newStr
docs: Given output of dmsetup ls this will return
      themajor:minor (block name) of the device deviceName