def global_max(col_vals, index):
 col_vals_without_None = [x for x in col_vals if (x is not None)]
 (max_col, min_col) = zip(*col_vals_without_None)
 return (max(max_col), min(min_col))

def global_max ( col_vals , index ) : col_vals_without_None = [ x for x in col_vals if ( x is not None ) ] ( max_col , min_col ) = zip ( * col_vals_without_None ) return ( max ( max_col ) , min ( min_col ) )
returns the global maximum and minimum .