How to use the apispec.ext.marshmallow.openapi.OpenAPIConverter function in apispec

LazyDict, OrderedLazyDict,
    )
except ImportError:
    from py_meta_utils import OptionalClass as BaseOpenAPIConverter
    from py_meta_utils import OptionalClass as LazyDict
    from py_meta_utils import OptionalClass as OrderedLazyDict

try:
    from marshmallow.compat import iteritems
    from marshmallow.utils import is_collection
except ImportError:
    from py_meta_utils import OptionalClass as iteritems
    from py_meta_utils import OptionalClass as is_collection


class OpenAPIConverter(BaseOpenAPIConverter):
    def fields2jsonschema(self, fields, schema=None, use_refs=True, dump=True, name=None):
        """Return the JSON Schema Object for a given marshmallow
        :class:`Schema `. Schema may optionally provide the ``title`` and
        ``description`` class Meta options.

        https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#schemaObject

        Example: ::

            class UserSchema(Schema):
                _id = fields.Int()
                email = fields.Email(description='email address of the user')
                name = fields.Str()

                class Meta:
                    title = 'User'

try:
    from apispec.ext.marshmallow.openapi import OpenAPIConverter
    openapi = OpenAPIConverter(openapi_version='2.0')
    fields2jsonschema = openapi.fields2jsonschema
    field2property = openapi.field2property
except ImportError:
    from apispec.ext.marshmallow.swagger import fields2jsonschema, field2property

import flask_marshmallow
from werkzeug import cached_property

from flask_restplus.model import Model as OriginalModel


class SchemaMixin(object):

    def __deepcopy__(self, memo):
        # XXX: Flask-RESTplus makes unnecessary data copying, while
        # marshmallow.Schema doesn't support deepcopyng.

# coding: utf-8
import inspect

from flask.views import MethodView

import flasgger

try:
    from marshmallow import Schema, fields
    from apispec.ext.marshmallow import openapi
    from apispec import APISpec as BaseAPISpec

    openapi_converter = openapi.OpenAPIConverter(
        openapi_version='2.0',
        schema_name_resolver=None,
        spec=None
    )
    schema2jsonschema = openapi_converter.schema2jsonschema
    schema2parameters = openapi_converter.schema2parameters
except ImportError:
    Schema = None
    fields = None
    schema2jsonschema = lambda schema: {}  # noqa
    schema2parameters = lambda schema: []  # noqa
    BaseAPISpec = object


class APISpec(BaseAPISpec):
    """

import collections
import uuid

import marshmallow
from apispec.ext.marshmallow.openapi import OpenAPIConverter
from marshmallow import fields, ValidationError
from marshmallow.base import FieldABC

from channelstream.server_state import get_state

converter = OpenAPIConverter("2.0.0", schema_name_resolver=lambda: None, spec=None)


MSG_EDITABLE_KEYS = ("uuid", "timestamp", "user", "message", "edited")


try:
    base_types = (unicode, basestring)
except NameError:
    base_types = (str,)


def gen_uuid():
    return uuid.uuid4()


def validate_connection_id(conn_id):

try:
    from apispec.ext.marshmallow.openapi import OpenAPIConverter
    openapi = OpenAPIConverter(openapi_version='2.0')
    schema2parameters = openapi.schema2parameters
except ImportError:
    from apispec.ext.marshmallow.swagger import schema2parameters

from flask_restplus.swagger import Swagger as OriginalSwagger


class Swagger(OriginalSwagger):

    def parameters_for(self, doc):
        schema = doc['params']

        if not schema:
            return []
        if isinstance(schema, list):
            return schema