def update_value(self, uid, **kwargs):
contacts = Contacts(self.base_uri, self.auth)<EOL>return self.update_subresource_instance(uid, body=kwargs,<EOL>subresource=contacts,<EOL>slug="<STR_LIT>")<EOL>
Updates contact's custom field value.
Returns :class:`Contact` object contains id and link to Contact.

:Example:

client.custom_fields.update_value(uid=1900901, contact_id=192012, value="abc")

:param int uid:        The unique id of the CustomField to update a value. Required.
:param int contactId:  The unique id of the Contact to update value. Required.
:param str value:      Value of CustomField. Required.