code: def registerParentFlag(self, optionName, value):
          '''Register a flag of a parent command
  
          :Parameters:
              - `optionName`: String. Name of option
              - `value`: Mixed. Value of parsed flag`
          '''
          self.parentFlags.update({optionName: value})
          return self registerParentFlag(self, optionName, value):
          '''Register a flag of a parent command
  
          :Parameters:
              - `optionName`: String. Name of option
              - `value`: Mixed. Value of parsed flag`
          '''
          self.parentFlags.update({optionName: value})
          return self
docs: Register a flag of a parent command
  
          :Parameters:
              - `optionName`: String. Name of option
              - `value`: Mixed. Value of parsed flag`