class_docstr: Subclass of Function that allows multiple functions and variables to
  be defined in a single code string. The code must contain a main() function
  definition.
class_docstr_tok: ["Subclass","of","Function","that","allows","multiple","functions","and","variables","to","be","defined","in","a","single","code","string",".","The","code","must","contain","a","main","(",")","function","definition","."]
code: def remove_callback(self, hook, func):
      self._chains[hook].remove(func)
  
imports: from collections import OrderedDict
  import logging
  import re
  import numpy
  from ...util.eq import eq
  from ...util import logger
  from .None import parsing
  from .shader_object import ShaderObject
  from .variable import Variable, Varying
  from .expression import TextExpression, FunctionCall
label_desc: Use image node_id 8 for calling the MainFunction obj's underlying member method code with example usage: obj.remove_callback(hook, func) without return types