class_docstr: Wrap an iterator and allow pushing back an item.
class_docstr_tok: ["Wrap","an","iterator","and","allow","pushing","back","an","item","."]
code: def __init__(self, x):
      self.iter = iter(x)
      self._nextitem = None
  
imports: import re
  from pygments.lexer import Lexer, RegexLexer, do_insertions, bygroups, words
  from pygments.token import Punctuation, Whitespace, Error, Text, Comment, Operator, Keyword, Name, String, Number, Generic
  from pygments.lexers import get_lexer_by_name, ClassNotFound
  from pygments.util import iteritems
  from pygments.lexers._postgres_builtins import KEYWORDS, DATATYPES, PSEUDO_TYPES, PLPGSQL_KEYWORDS
  from pygments.lexers import _tsql_builtins
label_desc: Use image node_id 1 to create a new lookahead object from inherited base classes: object with example: obj = lookahead(x)