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 __init__(self, shader_type, *args, **kwargs):
      self.shader_type = shader_type
      self._chains = {}
      Function.__init__(self, *args, **kwargs)
  
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 1 to create a new MainFunction object from inherited base classes: Function with example: obj = MainFunction(shader_type)