input: Write a function to normalize text by converting it to lowercase and removing non-alphanumeric characters.
  assert normalize_text('Welcome to the GPT Normalization Task!') == 'welcome to the gpt normalization task'
  assert normalize_text('Normalize THIS Text, Please!!!') == 'normalize this text please'
  assert normalize_text('123 EASY as ABC.') == '123 easy as abc'
output: def normalize_text(text):
      import re
      text = text.lower()
      text = re.sub(r'[^a-zA-Z0-9\s]', '', text)
      return text