code: def _create_encode_signature(
      channel_infos: Dict[str, ChannelInfo],
  ) -> str:
      signature_args: list[str] = ["self"]
      docstring_parameters: list[str] = [
          "",
          "Parameters",
          "----------",
          "",
      ]
      for channel, info in channel_infos.items():
          field_class_name = info.field_class_name
          assert (
              field_class_name is not None
          ), "All channels are expected to have a field class"
          datum_and_value_class_names = []
          if info.datum_class_name is not None:
              datum_and_value_class_names.append(info.datum_class_name)
  
          if info.value_class_name is not None:
              datum_and_value_class_names.append(info.value_class_name)
  
          # dict stands for the return types of alt.datum, alt.value as well as
          # the dictionary representation of an encoding channel class. See
          # discussions in https://github.com/altair-viz/altair/pull/3208
          # for more background.
          union_types = ["str", field_class_name, "dict"]
          docstring_union_types = [
              "str",
              rst_syntax_for_class(field_class_name),
              "Dict",
          ]
          if info.supports_arrays:
              # We could be more specific about what types are accepted in the list
              # but then the signatures would get rather long and less useful
              # to a user when it shows up in their IDE.
              union_types.append("list")
              docstring_union_types.append("List")
  
          union_types = (
              union_types
              + datum_and_value_class_names
              + ["UndefinedType"]
          )
          docstring_union_types = docstring_union_types + [
              rst_syntax_for_class(c)
              for c in datum_and_value_class_names
          ]
  
          signature_args.append(
              f"{channel}: Union[{', '.join(union_types)}] = Undefined"
          )
  
          docstring_parameters.append(
              f"{channel} : {', '.join(docstring_union_types)}"
          )
          docstring_parameters.append(
              "    {}".format(
                  process_description(info.deep_description)
              )
          )
      if len(docstring_parameters) > 1:
          docstring_parameters += [""]
      docstring = indent_docstring(
          docstring_parameters, indent_level=4, width=100, lstrip=True
      )
      return ENCODE_SIGNATURE.format(
          encode_method_args=", ".join(signature_args),
          docstring=docstring,
      )
  
imports: import argparse
  import copy
  import json
  import os
  import re
  import sys
  import textwrap
  from dataclasses import dataclass
  from os.path import abspath, dirname, join
  from typing import Dict, Final, List, Literal, Optional, Tuple, Type, Union
  from urllib import request
  import m2r
  from schemapi import codegen
  from schemapi.codegen import CodeSnippet
  from schemapi.utils import SchemaInfo, get_valid_identifier, resolve_references, ruff_format_str, rst_syntax_for_class, indent_docstring
label_desc: Use image node_id 16 for calling a global function with example usage: _create_encode_signature(channel_infos) and returns: ENCODE_SIGNATURE