code: def find_lexer_class(name):
      """Lookup a lexer class by name.
  
      Return None if not found.
      """
      if name in _lexer_cache:
          return _lexer_cache[name]
      # lookup builtin lexers
      for module_name, lname, aliases, _, _ in itervalues(LEXERS):
          if name == lname:
              _load_lexers(module_name)
              return _lexer_cache[name]
      # continue with lexers from setuptools entrypoints
      for cls in find_plugin_lexers():
          if cls.name == name:
              return cls
  
imports: import re
  import sys
  import types
  import fnmatch
  from os.path import basename
  from pygments.lexers._mapping import LEXERS
  from pygments.modeline import get_filetype_from_buffer
  from pygments.plugin import find_plugin_lexers
  from pygments.util import ClassNotFound, itervalues, guess_decode, text_type
label_desc: Use image node_id 4 for calling a global function with example usage: find_lexer_class(name) and returns: _lexer_cache, _lexer_cache, cls