code: def write(self,f):
          
          if isinstance(f,str):
              f = open(f,'w')
              f.write("pcf\n")
              f.write("* control data\n")
          for line in CONTROL_VARIABLE_LINES:
              [f.write(self.formatted_values[name.replace('[','').replace(']','')]) for name in line.split()]
              f.write('\n')
docs: write control data section to a file
          
          Parameters
          ----------
          f: file handle or string filename