code: def add_column(filename,column,formula,force=False):
      
      columns = parse_formula(formula)
      logger.info("Running file: %s"%filename)
      logger.debug("  Reading columns: %s"%columns)
      data = fitsio.read(filename,columns=columns)
  
      logger.debug('  Evaluating formula: %s'%formula)
      col = eval(formula)
  
      col = np.asarray(col,dtype=[(column,col.dtype)])
      insert_columns(filename,col,force=force)
      return True
docs: Add a column to a FITS file.
  
      ADW: Could this be replaced by a ftool?