class_docstr: Uses unicode.lower() to lowercase token text.
  
  >>> rext = RegexTokenizer()
  >>> stream = rext("This is a TEST")
  >>> [token.text for token in LowercaseFilter(stream)]
  ["this", "is", "a", "test"]
class_docstr_tok: ["Uses","unicode.lower","(",")","to","lowercase","token","text",".",">",">",">","rext","=","RegexTokenizer","(",")",">",">",">","stream","=","rext","(","``","This","is","a","TEST","''",")",">",">",">","[","token.text","for","token","in","LowercaseFilter","(","stream",")","]","[","``","this","''",",","``","is","''",",","``","a","''",",","``","test","''","]"]
code: def __call__(self, tokens):
      for t in tokens:
          t.text = t.text.lower()
          yield t
  
imports: from itertools import chain
  from whoosh.compat import next
  from whoosh.analysis.acore import Composable
  from whoosh.util.text import rcompile
label_desc: Use image node_id 1 for calling the LowercaseFilter obj's underlying member method code with example usage: obj.__call__(tokens) without return types