code: def checkUpdate(self, *args):
          
          g = get_root(self).globals
          if not self.check():
              g.clog.warn('Current observing parameters are not valid.')
              return False
  
          if not g.ipars.check():
              g.clog.warn('Current instrument parameters are not valid.')
              return False
docs: Updates values after first checking instrument parameters are OK.
          This is not integrated within update to prevent ifinite recursion
          since update gets called from ipars.