system: 
You are an expert in composing functions. You are given a question and a set of possible functions.
Based on the question, you will need to make one or more function/tool calls to achieve the purpose.
If none of the function can be used, point it out. If the given question lacks the parameters required by the function,
also point it out. You should only return the function call in tools call sections.

If you decide to invoke any of the function(s), you MUST put it in the format of [func_name1(params_name1=params_value1, params_name2=params_value2...), func_name2(params)]

You SHOULD NOT include any other text in the response.

Here is a list of functions in JSON format that you can invoke.

[{'name': 'default_function', 'description': 'This function serves as a placeholder and does not perform any operations. Note that the provided function is in Python 3 syntax.', 'parameters': {'type': 'dict', 'required': [], 'properties': {}}}, {'name': 'add_mtnards_server', 'description': 'Registers a new MTNA Rich Data Services (RDS) server with a given nickname and host, and associates it with the provided API key. Note that the provided function is in Python 3 syntax.', 'parameters': {'type': 'dict', 'required': ['nickname', 'api_key'], 'properties': {'nickname': {'type': 'string', 'description': 'A unique nickname for the server, used as an identifier within the environment.'}, 'host': {'type': 'string', 'description': "The server's hostname or IP address. Assumes 'localhost' if not specified.", 'default': 'localhost'}, 'api_key': {'type': 'string', 'description': 'The API key for authenticating with the RDS server. This key should be kept confidential.'}}}}, {'name': 'add_postgres_server', 'description': 'Registers a new PostgreSQL server within the application environment, allowing it to be used for database operations. Note that the provided function is in Python 3 syntax.', 'parameters': {'type': 'dict', 'required': ['nickname', 'host', 'port', 'database', 'username', 'password'], 'properties': {'nickname': {'type': 'string', 'description': 'A unique identifier or alias for the server.'}, 'host': {'type': 'string', 'description': "The server's hostname or IP address."}, 'port': {'type': 'integer', 'description': 'The network port on which the PostgreSQL server is listening. The default PostgreSQL port is 5432 if not specified.'}, 'database': {'type': 'string', 'description': 'The default database to use on the server.'}, 'username': {'type': 'string', 'description': 'The username for authentication with the PostgreSQL server.'}, 'password': {'type': 'string', 'description': 'The password associated with the username for authentication. It should be kept secret.'}}}}, {'name': 'connect_to_server', 'description': 'Establishes a connection to the specified server or verifies if the connection is possible. Note that the provided function is in Python 3 syntax.', 'parameters': {'type': 'dict', 'required': ['nickname'], 'properties': {'nickname': {'type': 'string', 'description': 'A unique identifier or alias for the server to which a connection is being established.'}, 'timeout': {'type': 'integer', 'description': 'The maximum amount of time in seconds to wait for the connection to be established before timing out.', 'default': 30}, 'use_ssl': {'type': 'boolean', 'description': 'Specifies whether to use SSL encryption for the connection.', 'default': True}, 'port': {'type': 'integer', 'description': 'The port number on the server to connect to.', 'default': 22}}}}, {'name': 'rename_server', 'description': 'Renames a server by changing its current identifier to a new one provided by the user. Note that the provided function is in Python 3 syntax.', 'parameters': {'type': 'dict', 'required': ['_from', 'to'], 'properties': {'_from': {'type': 'string', 'description': 'The current server identifier, such as a hostname or IP address.'}, 'to': {'type': 'string', 'description': 'The new server identifier to which the server will be renamed. This should be unique and adhere to naming conventions.'}}}}, {'name': 'list_servers', 'description': 'List all the servers in the environment based on the specified server type. If no type is specified, all servers are listed. Note that the provided function is in Python 3 syntax.', 'parameters': {'type': 'dict', 'properties': {'type': {'type': 'string', 'description': "The type of server to filter the list by. If 'all' is specified or this parameter is omitted, servers of all types will be listed.", 'enum': ['all', 'graphql', 'mtna', 'openapi', 'postgres', 'rds', 'sql'], 'default': 'all'}}, 'required': []}}, {'name': 'list_files', 'description': 'List all files of a specified type within the current project directory. Note that the provided function is in Python 3 syntax.', 'parameters': {'type': 'dict', 'properties': {'type': {'type': 'string', 'description': "The file extension type to filter the files in the project. For example, 'py' for Python files.", 'enum': ['py', 'txt', 'md', 'json'], 'default': 'py'}, 'include_hidden': {'type': 'boolean', 'description': "A flag to determine if hidden files should be included in the list. Hidden files start with a dot ('.').", 'default': False}}, 'required': []}}, {'name': 'open_project', 'description': 'Initializes a new Data Artifex project or opens an existing one in the specified directory. Note that the provided function is in Python 3 syntax.', 'parameters': {'type': 'dict', 'required': ['path'], 'properties': {'path': {'type': 'string', 'description': 'The filesystem path to the directory where the project files are located or will be created. The path should be absolute or relative to the current working directory.'}, 'create_new': {'type': 'boolean', 'description': 'A flag indicating whether to create a new project if one does not exist at the specified path.', 'default': False}, 'access_mode': {'type': 'string', 'description': "The mode in which to open the project. For example, 'read-only' or 'edit'.", 'enum': ['read-only', 'edit'], 'default': 'edit'}}}}, {'name': 'close_project', 'description': 'This function closes the currently active data artifex project, ensuring all resources are properly released and saved. Note that the provided function is in Python 3 syntax.', 'parameters': {'type': 'dict', 'properties': {'save_state': {'type': 'boolean', 'description': 'Determines whether the current state of the project should be saved before closing.', 'default': True}, 'confirmation': {'type': 'string', 'description': "A confirmation message to ensure accidental closure is prevented. Expected format: 'CONFIRM' to proceed with closure.", 'enum': ['CONFIRM'], 'default': 'CONFIRM'}, 'timeout': {'type': 'integer', 'description': 'The maximum number of seconds to wait for closure before timing out. A value of 0 means immediate closure.', 'default': 30}}, 'required': []}}, {'name': 'dartfx_help', 'description': 'Provides assistance to the user on a particular topic by displaying relevant help information. Note that the provided function is in Python 3 syntax.', 'parameters': {'type': 'dict', 'required': ['topic'], 'properties': {'topic': {'type': 'string', 'description': 'The specific topic for which help is requested. It should be a recognizable keyword or phrase.'}, 'search_deep': {'type': 'boolean', 'description': 'Specifies whether to perform a deep search in the help database. A deep search may take longer but yields comprehensive results.', 'default': False}, 'language': {'type': 'string', 'description': 'The language in which to provide the help information.', 'enum': ['English', 'Spanish', 'French', 'German', 'Mandarin'], 'default': 'English'}, 'format': {'type': 'string', 'description': 'The format in which the help information should be presented to the user.', 'enum': ['text', 'audio', 'video'], 'default': 'text'}}}}]


user: Could you provide me with a list of all the PostgreSQL servers currently set up in our environment?

Available functions:
[{"name": "default_function", "description": "This function serves as a placeholder and does not perform any operations.", "parameters": {"type": "dict", "required": [], "properties": {}}}, {"name": "add_mtnards_server", "description": "Registers a new MTNA Rich Data Services (RDS) server with a given nickname and host, and associates it with the provided API key.", "parameters": {"type": "dict", "required": ["nickname", "api_key"], "properties": {"nickname": {"type": "string", "description": "A unique nickname for the server, used as an identifier within the environment."}, "host": {"type": "string", "description": "The server's hostname or IP address. Assumes 'localhost' if not specified.", "default": "localhost"}, "api_key": {"type": "string", "description": "The API key for authenticating with the RDS server. This key should be kept confidential."}}}}, {"name": "add_postgres_server", "description": "Registers a new PostgreSQL server within the application environment, allowing it to be used for database operations.", "parameters": {"type": "dict", "required": ["nickname", "host", "port", "database", "username", "password"], "properties": {"nickname": {"type": "string", "description": "A unique identifier or alias for the server."}, "host": {"type": "string", "description": "The server's hostname or IP address."}, "port": {"type": "integer", "description": "The network port on which the PostgreSQL server is listening. The default PostgreSQL port is 5432 if not specified."}, "database": {"type": "string", "description": "The default database to use on the server."}, "username": {"type": "string", "description": "The username for authentication with the PostgreSQL server."}, "password": {"type": "string", "description": "The password associated with the username for authentication. It should be kept secret."}}}}, {"name": "connect_to_server", "description": "Establishes a connection to the specified server or verifies if the connection is possible.", "parameters": {"type": "dict", "required": ["nickname"], "properties": {"nickname": {"type": "string", "description": "A unique identifier or alias for the server to which a connection is being established."}, "timeout": {"type": "integer", "description": "The maximum amount of time in seconds to wait for the connection to be established before timing out.", "default": 30}, "use_ssl": {"type": "boolean", "description": "Specifies whether to use SSL encryption for the connection.", "default": true}, "port": {"type": "integer", "description": "The port number on the server to connect to.", "default": 22}}}}, {"name": "rename_server", "description": "Renames a server by changing its current identifier to a new one provided by the user.", "parameters": {"type": "dict", "required": ["_from", "to"], "properties": {"_from": {"type": "string", "description": "The current server identifier, such as a hostname or IP address."}, "to": {"type": "string", "description": "The new server identifier to which the server will be renamed. This should be unique and adhere to naming conventions."}}}}, {"name": "list_servers", "description": "List all the servers in the environment based on the specified server type. If no type is specified, all servers are listed.", "parameters": {"type": "dict", "properties": {"type": {"type": "string", "description": "The type of server to filter the list by. If 'all' is specified or this parameter is omitted, servers of all types will be listed.", "enum": ["all", "graphql", "mtna", "openapi", "postgres", "rds", "sql"], "default": "all"}}, "required": []}}, {"name": "list_files", "description": "List all files of a specified type within the current project directory.", "parameters": {"type": "dict", "properties": {"type": {"type": "string", "description": "The file extension type to filter the files in the project. For example, 'py' for Python files.", "enum": ["py", "txt", "md", "json"], "default": "py"}, "include_hidden": {"type": "boolean", "description": "A flag to determine if hidden files should be included in the list. Hidden files start with a dot ('.').", "default": false}}, "required": []}}, {"name": "open_project", "description": "Initializes a new Data Artifex project or opens an existing one in the specified directory.", "parameters": {"type": "dict", "required": ["path"], "properties": {"path": {"type": "string", "description": "The filesystem path to the directory where the project files are located or will be created. The path should be absolute or relative to the current working directory."}, "create_new": {"type": "boolean", "description": "A flag indicating whether to create a new project if one does not exist at the specified path.", "default": false}, "access_mode": {"type": "string", "description": "The mode in which to open the project. For example, 'read-only' or 'edit'.", "enum": ["read-only", "edit"], "default": "edit"}}}}, {"name": "close_project", "description": "This function closes the currently active data artifex project, ensuring all resources are properly released and saved.", "parameters": {"type": "dict", "properties": {"save_state": {"type": "boolean", "description": "Determines whether the current state of the project should be saved before closing.", "default": true}, "confirmation": {"type": "string", "description": "A confirmation message to ensure accidental closure is prevented. Expected format: 'CONFIRM' to proceed with closure.", "enum": ["CONFIRM"], "default": "CONFIRM"}, "timeout": {"type": "integer", "description": "The maximum number of seconds to wait for closure before timing out. A value of 0 means immediate closure.", "default": 30}}, "required": []}}, {"name": "dartfx_help", "description": "Provides assistance to the user on a particular topic by displaying relevant help information.", "parameters": {"type": "dict", "required": ["topic"], "properties": {"topic": {"type": "string", "description": "The specific topic for which help is requested. It should be a recognizable keyword or phrase."}, "search_deep": {"type": "boolean", "description": "Specifies whether to perform a deep search in the help database. A deep search may take longer but yields comprehensive results.", "default": false}, "language": {"type": "string", "description": "The language in which to provide the help information.", "enum": ["English", "Spanish", "French", "German", "Mandarin"], "default": "English"}, "format": {"type": "string", "description": "The format in which the help information should be presented to the user.", "enum": ["text", "audio", "video"], "default": "text"}}}}]

Ground-truth function call:
[{"list_servers": {"type": ["postgres"]}}]