How to use the trytond.model.fields.Char function in trytond

pool = Pool()
        super(ActionActWindowView, cls).write(windows, values, *args)
        pool.get('ir.action.keyword')._get_keyword_cache.clear()

    @classmethod
    def delete(cls, windows):
        pool = Pool()
        super(ActionActWindowView, cls).delete(windows)
        pool.get('ir.action.keyword')._get_keyword_cache.clear()


class ActionActWindowDomain(
        sequence_ordered(), DeactivableMixin, ModelSQL, ModelView):
    "Action act window domain"
    __name__ = 'ir.action.act_window.domain'
    name = fields.Char('Name', translate=True)
    domain = fields.Char('Domain')
    count = fields.Boolean('Count')
    act_window = fields.Many2One('ir.action.act_window', 'Action',
        select=True, required=True, ondelete='CASCADE')

    @classmethod
    def __register__(cls, module_name):
        super().__register__(module_name)

        table = cls.__table_handler__(module_name)

        # Migration from 5.0: remove required on sequence
        table.not_null_action('sequence', 'remove')

    @classmethod
    def default_count(cls):

)
from trytond.model import ModelView, ModelSQL, fields
from trytond.pool import Pool, PoolMeta
from trytond.transaction import Transaction
from trytond import backend

__all__ = ['Tag', 'TaskTags']
__metaclass__ = PoolMeta


class Tag(ModelSQL, ModelView):
    "Tags"
    __name__ = "project.work.tag"

    name = fields.Char('Name', required=True)
    color = fields.Char('Color Code', required=True)
    project = fields.Many2One(
        'project.work', 'Project', required=True,
        domain=[('type', '=', 'project')], ondelete='CASCADE',
    )

    @classmethod
    def __setup__(cls):
        super(Tag, cls).__setup__()
        cls._sql_constraints += [
            ('unique_name_project', 'UNIQUE(name, project)', 'Duplicate Tag')
        ]

    @staticmethod
    def default_color():
        '''
        Default for color

help="RFC 4646 tag: http://tools.ietf.org/html/rfc4646")
    translatable = fields.Boolean('Translatable', readonly=True)
    parent = fields.Char("Parent Code", help="Code of the exceptional parent")
    direction = fields.Selection([
            ('ltr', 'Left-to-right'),
            ('rtl', 'Right-to-left'),
            ], 'Direction', required=True)

    # date
    date = fields.Char('Date', required=True)

    am = fields.Char("AM")
    pm = fields.Char("PM")

    # number
    grouping = fields.Char('Grouping', required=True)
    decimal_point = fields.Char('Decimal Separator', required=True)
    thousands_sep = fields.Char('Thousands Separator')

    # monetary formatting
    mon_grouping = fields.Char('Grouping', required=True)
    mon_decimal_point = fields.Char('Decimal Separator', required=True)
    mon_thousands_sep = fields.Char('Thousands Separator')
    p_sign_posn = fields.Integer('Positive Sign Position', required=True)
    n_sign_posn = fields.Integer('Negative Sign Position', required=True)
    positive_sign = fields.Char('Positive Sign')
    negative_sign = fields.Char('Negative Sign')
    p_cs_precedes = fields.Boolean('Positive Currency Symbol Precedes')
    n_cs_precedes = fields.Boolean('Negative Currency Symbol Precedes')
    p_sep_by_space = fields.Boolean('Positive Separate by Space')
    n_sep_by_space = fields.Boolean('Negative Separate by Space')

"Language"
    __name__ = "ir.lang"
    name = fields.Char('Name', required=True, translate=True)
    code = fields.Char('Code', required=True,
        help="RFC 4646 tag: http://tools.ietf.org/html/rfc4646")
    translatable = fields.Boolean('Translatable', readonly=True)
    parent = fields.Char("Parent Code", help="Code of the exceptional parent")
    direction = fields.Selection([
            ('ltr', 'Left-to-right'),
            ('rtl', 'Right-to-left'),
            ], 'Direction', required=True)

    # date
    date = fields.Char('Date', required=True)

    am = fields.Char("AM")
    pm = fields.Char("PM")

    # number
    grouping = fields.Char('Grouping', required=True)
    decimal_point = fields.Char('Decimal Separator', required=True)
    thousands_sep = fields.Char('Thousands Separator')

    # monetary formatting
    mon_grouping = fields.Char('Grouping', required=True)
    mon_decimal_point = fields.Char('Decimal Separator', required=True)
    mon_thousands_sep = fields.Char('Thousands Separator')
    p_sign_posn = fields.Integer('Positive Sign Position', required=True)
    n_sign_posn = fields.Integer('Negative Sign Position', required=True)
    positive_sign = fields.Char('Positive Sign')
    negative_sign = fields.Char('Negative Sign')
    p_cs_precedes = fields.Boolean('Positive Currency Symbol Precedes')

# This file is part of Tryton.  The COPYRIGHT file at the top level of
# this repository contains the full copyright notices and license terms.
from trytond.cache import Cache
from trytond.config import config
from trytond.model import ModelSQL, ModelSingleton, fields


class Configuration(ModelSingleton, ModelSQL):
    'Configuration'
    __name__ = 'ir.configuration'
    language = fields.Char('language')
    hostname = fields.Char("Hostname")
    _get_language_cache = Cache('ir_configuration.get_language')

    @staticmethod
    def default_language():
        return config.get('database', 'language')

    @classmethod
    def get_language(cls):
        language = cls._get_language_cache.get(None)
        if language is not None:
            return language
        config = cls(1)
        language = config.language
        if not language:
            language = config.get('database', 'language')

states={
            'readonly': Bool(Eval('module')),
            },
        depends=['module'])
    relation = fields.Char('Model Relation',
        states={
            'readonly': Bool(Eval('module')),
            },
        depends=['module'])
    model = fields.Many2One('ir.model', 'Model', required=True,
        select=True, ondelete='CASCADE',
        states={
            'readonly': Bool(Eval('module')),
            },
        depends=['module'])
    field_description = fields.Char('Field Description', translate=True,
        loading='lazy',
        states={
            'readonly': Bool(Eval('module')),
            },
        depends=['module'])
    ttype = fields.Char('Field Type',
        states={
            'readonly': Bool(Eval('module')),
            },
        depends=['module'])
    help = fields.Text('Help', translate=True, loading='lazy',
        states={
            'readonly': Bool(Eval('module')),
            },
        depends=['module'])
    module = fields.Char('Module',

parent = fields.Char("Parent Code", help="Code of the exceptional parent")
    direction = fields.Selection([
            ('ltr', 'Left-to-right'),
            ('rtl', 'Right-to-left'),
            ], 'Direction', required=True)

    # date
    date = fields.Char('Date', required=True)

    am = fields.Char("AM")
    pm = fields.Char("PM")

    # number
    grouping = fields.Char('Grouping', required=True)
    decimal_point = fields.Char('Decimal Separator', required=True)
    thousands_sep = fields.Char('Thousands Separator')

    # monetary formatting
    mon_grouping = fields.Char('Grouping', required=True)
    mon_decimal_point = fields.Char('Decimal Separator', required=True)
    mon_thousands_sep = fields.Char('Thousands Separator')
    p_sign_posn = fields.Integer('Positive Sign Position', required=True)
    n_sign_posn = fields.Integer('Negative Sign Position', required=True)
    positive_sign = fields.Char('Positive Sign')
    negative_sign = fields.Char('Negative Sign')
    p_cs_precedes = fields.Boolean('Positive Currency Symbol Precedes')
    n_cs_precedes = fields.Boolean('Negative Currency Symbol Precedes')
    p_sep_by_space = fields.Boolean('Positive Separate by Space')
    n_sep_by_space = fields.Boolean('Negative Separate by Space')

    _lang_cache = Cache('ir.lang')
    _code_cache = Cache('ir.lang.code', context=False)

class Translation(ModelSQL, ModelView):
    "Translation"
    __name__ = "ir.translation"

    name = fields.Char('Field Name', required=True)
    res_id = fields.Integer('Resource ID', select=True, required=True)
    lang = fields.Selection('get_language', string='Language')
    type = fields.Selection(TRANSLATION_TYPE, string='Type',
       required=True)
    src = fields.Text('Source')
    value = fields.Text('Translation Value')
    module = fields.Char('Module', readonly=True)
    fuzzy = fields.Boolean('Fuzzy')
    model = fields.Function(fields.Char('Model'), 'get_model',
            searcher='search_model')
    overriding_module = fields.Char('Overriding Module', readonly=True)
    _translation_cache = Cache('ir.translation', size_limit=10240,
        context=False)
    _get_language_cache = Cache('ir.translation.get_language')

    @classmethod
    def __register__(cls, module_name):
        transaction = Transaction()
        cursor = transaction.connection.cursor()
        ir_translation = cls.__table__()
        table = cls.__table_handler__(module_name)

        # Migration from 5.0: remove src_md5
        if table.column_exist('src_md5'):
            table.drop_constraint('translation_md5_uniq')
            table.drop_column('src_md5')

store_prefix = config.get('attachment', 'store_prefix', default=None)
else:
    file_id = None
    store_prefix = None


class Attachment(ResourceMixin, ModelSQL, ModelView):
    "Attachment"
    __name__ = 'ir.attachment'
    name = fields.Char('Name', required=True)
    type = fields.Selection([
        ('data', 'Data'),
        ('link', 'Link'),
        ], 'Type', required=True)
    description = fields.Text('Description')
    summary = fields.Function(fields.Char('Summary'), 'on_change_with_summary')
    link = fields.Char('Link', states={
            'invisible': Eval('type') != 'link',
            }, depends=['type'])
    data = fields.Binary('Data', filename='name',
        file_id=file_id, store_prefix=store_prefix,
        states={
            'invisible': Eval('type') != 'data',
            }, depends=['type'])
    file_id = fields.Char('File ID', readonly=True)
    data_size = fields.Function(fields.Integer('Data size', states={
                'invisible': Eval('type') != 'data',
                }, depends=['type']), 'get_size')

    @classmethod
    def __setup__(cls):
        super().__setup__()

return res


class RequestHistory(ModelSQL, ModelView):
    "Request history"
    __name__ = 'res.request.history'
    name = fields.Char('Summary', required=True, readonly=True)
    request = fields.Many2One('res.request', 'Request', required=True,
       ondelete='CASCADE', select=True, readonly=True)
    act_from = fields.Many2One('res.user', 'From', required=True,
       readonly=True)
    act_to = fields.Many2One('res.user', 'To', required=True, readonly=True)
    body = fields.Text('Body', readonly=True)
    date_sent = fields.DateTime('Date sent', required=True, readonly=True)
    state = fields.Selection(_STATES, 'State', required=True, readonly=True)
    subject = fields.Char('Subject', required=True, readonly=True)
    number_references = fields.Integer('References', readonly=True)
    priority = fields.Selection(_PRIORITIES, 'Priority', required=True,
            readonly=True)

    @classmethod
    def __setup__(cls):
        super(RequestHistory, cls).__setup__()
        cls._order.insert(0, ('date_sent', 'DESC'))

    @staticmethod
    def default_name():
        return 'No Name'

    @staticmethod
    def default_act_from():
        return int(Transaction().user)