8.4.3 unflag(self,channel=-1,phase=-1,flag=1):

unflag $<$ DataAna(BoaDataEntity.DataEntity): $<$ BoaDataAnalyser.py

    NAM: unflag (method)  
    DES: Unflag data, i.e. reset to 0.
	 Might want to change to allow for list of channels
    INP: 
         (i) channel  =  -1 : all channels; 0=first channel
         (i) phase    =  -1 : all; else: 0,1,2
         (i) flag     =   1 : unflag only this value