Write a function that finds all non-numeric rows in the 'Reviews' column of dataframe 'df1' using regex

def is_numeric(s):
  return bool(re.search(r'^(\d+)$', s))

df1 = pd.DataFrame({"Reviews": ["1", "2", "3", "4", "5", "apple", "orange"]})

df1[~df1["Reviews"].apply(is_numeric)]