There is Pandas dataframe: surgery age rectal_temp pulse respiratory_rate extremities_temp pain outcome 0 38.50 66 3 3 ? 2 ? 0 1 39.2 88 ? ? 4 1 ? 0 2 38.30 40 1 1 3 1 ? 0 3 39.10 164 4 1 6 2 1 0 4 37.30 104 ? ? 6 2 ? 0 Write a function that will change the parameters of all columns to int64

def to_int64(df):
  for i in df.columns:
    df[i] = df[i].astype('int64')
  return df