Modify the formula below so that it rounds to the nearest integer, but not less than 1 and not more than 4: df2['respiratory_rate'] = df2['respiratory_rate'].fillna( df2.groupby('pulse')['respiratory_rate'].transform('median'))

def rounder(x):
  if x < 1:
    return 1
  if x > 4:
    return 4
  else:
    return round(x)
  
df2['respiratory_rate'] = df2['respiratory_rate'].apply(rounder)