class_docstr: Helper object that allows to configure `characters` strategy with
  various unicode categories and characters. Also allows negation of
  configured set.
  
  :param negate: If True, configure :func:`hypothesis.strategies.characters`
      to match anything other than configured character set
  :param flags: Regex flags. They affect how and which characters are matched
code: def __init__(self, negate=False, flags=0):
      self._categories = set()
      self._whitelist_chars = set()
      self._blacklist_chars = set()
      self._negate = negate
      self._ignorecase = flags & re.IGNORECASE
      self._unicode = (
          not bool(flags & re.ASCII)
          if PY3
          else bool(flags & re.UNICODE)
      )
      self.code_to_char = hunichr
  
imports: from __future__ import absolute_import, division, print_function
  import operator
  import re
  import sre_constants
  import sre_parse
  import sys
  import hypothesis.strategies
  from hypothesis import reject
  from hypothesis.internal.charmap import as_general_categories, categories
  from hypothesis.internal.compat import PY3, hrange, hunichr, int_to_byte, text_type
label_desc: Use image node_id 1 to create a new CharactersBuilder object from inherited base classes: object with example: obj = CharactersBuilder(negate, flags)