code: def NgramAnalyzer(minsize, maxsize=None):
      """Composes an NgramTokenizer and a LowercaseFilter.
  
      >>> ana = NgramAnalyzer(4)
      >>> [token.text for token in ana("hi there")]
      ["hi t", "i th", " the", "ther", "here"]
      """
  
      return (
          NgramTokenizer(minsize, maxsize=maxsize) | LowercaseFilter()
      )
  
file_path: whoosh/src/whoosh/analysis/ngrams.py
imports: from whoosh.compat import text_type
  from whoosh.compat import xrange
  from whoosh.analysis.acore import Token
  from whoosh.analysis.filters import Filter, LowercaseFilter
  from whoosh.analysis.tokenizers import Tokenizer, RegexTokenizer
label_desc: Use image node_id 1 for calling a global function with example usage: NgramAnalyzer(minsize, maxsize) and returns: unknown