code: def input_preprocessing(sent: str, lang: str):
      """Function for preprocessing the input texts. The function first does
      some basic tokenization. For English, it then also processes Greek letters
      such as Δ or λ (if any).
  
      Args:
          sent: input text.
          lang: language
  
      Returns: preprocessed input text.
      """
      # Basic Preprocessing and Tokenization
      if lang == constants.ENGLISH:
          sent = sent.replace("+", " plus ")
          sent = sent.replace("=", " equals ")
          sent = sent.replace("@", " at ")
          sent = sent.replace("*", " times ")
          # Greek letters processing
          for jx, tok in enumerate(sent):
              if tok in constants.EN_GREEK_TO_SPOKEN:
                  sent = (
                      sent[:jx]
                      + constants.EN_GREEK_TO_SPOKEN[tok]
                      + sent[jx + 1 :]
                  )
  
      sent = convert_superscript(sent)
      sent = convert_fraction(sent)
      sent = add_space_around_dash(sent)
  
      return sent
  
file_path: NeMo/nemo/collections/nlp/data/text_normalization/utils.py
imports: import string
  from copy import deepcopy
  import regex
  from tqdm import tqdm
  from nemo.collections.nlp.data.text_normalization import constants
label_desc: Use image node_id 5 for calling a global function with example usage: input_preprocessing(sent, lang) and returns: sent