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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _build_string_type(var, property_path=None):
 """ Builds schema definitions for string type values. :param var: The string type value :param List[str] property_path: The property path of the current type, defaults to None, optional :param property_path: [type], optional :return: The built schema definition :rtype: Dict[str, Any] """


    if not property_path:
        property_path = []

    schema = {"type": "string"}
    if is_builtin_type(var):
        return schema

    if is_regex_type(var):
        schema["pattern"] = var.__supertype__.pattern
        return schema

    if is_config_var(var):
        schema.update(
            _build_attribute_modifiers(var, {"min": "minLength", "max": "maxLength"})
        )
        if is_regex_type(var.type):
            schema["pattern"] = var.type.__supertype__.pattern

    return schema