human
Solve the following python programming problem given the following code:
@ util.positional (2) 
def format_proto_file(file_descriptor, output, indent_space = 2) : 
    out = generate.IndentWriter (output, indent_space = indent_space) 
    if file_descriptor.package : 
        (out << ('package %s;' % file_descriptor.package)) 
def write_enums(enum_descriptors) : 
        'Write nested and non-nested Enum types.

    Args:
      enum_descriptors: List of EnumDescriptor objects from which to generate
        enums.
    ' 
        for enum in (enum_descriptors or []) : 
            (out << '') 
            (out << '') 
            (out << ('enum %s {' % enum.name)) 
            (out << '') 
            with out.indent () : 
                if enum.values : 
                    for enum_value in enum.values : 
                        (out << ('%s = %s;' % (enum_value.name, enum_value.number))) 
(out << '}') 
write_enums (file_descriptor.enum_types) 
    def write_fields(field_descriptors) : 
        'Write fields for Message types.

    Args:
      field_descriptors: List of FieldDescriptor objects from which to generate
        fields.
    ' 
        for field in (field_descriptors or []) : 
            default_format = '' 
            if (field.default_value is not None) : 
                if (field.label == descriptor.FieldDescriptor.Label.REPEATED) : 
                    logging.warning (('Default value for repeated field %s is not being written to proto file' % field.name)) 
else : 
                    if (field.variant == messages.Variant.MESSAGE) : 
                        logging.warning (('Message field %s should not have default values' % field.name)) 
                        default = None 
else : 
                        if (field.variant == messages.Variant.STRING) : 
                            default = repr (field.default_value.encode ('utf-8')) 
else : 
                            if (field.variant == messages.Variant.BYTES) : 
                                default = repr (field.default_value) 
else : 
                                default = str...

    
    

    Fix the buggy line: write_messages (output.message_types)
assistant
#Here is Python code to fix the buggy line: write_messages (output.

write_messages (file_descriptor.message_types)