code: def hasMZSignature(self, rd): 
          
          rd.setOffset(0)
          sign = rd.read(2)
          if sign == "MZ":
              return True
          return False
docs: Check for MZ signature.
  
          @type rd: L{ReadData}
          @param rd: A L{ReadData} object.
  
          @rtype: bool
          @return: True is the given L{ReadData} stream has the MZ signature. Otherwise, False.