class_docstr: This handler handles connection and execution of the DuckDB statements.
docstr: Connect to a DuckDB database.
  
  Returns:
      DuckDBPyConnection: The database connection.
docstr_tok: ["Connect","to","a","DuckDB","database",".","Returns",":","DuckDBPyConnection",":","The","database","connection","."]
code: def connect(self) -> DuckDBPyConnection:
      """Connect to a DuckDB database.
  
      Returns:
          DuckDBPyConnection: The database connection.
      """
  
      if self.is_connected is True:
          return self.connection
  
      args = {
          "database": self.connection_data.get("database"),
          "read_only": self.connection_data.get("read_only"),
      }
  
      self.connection = duckdb.connect(**args)
      self.is_connected = True
  
      return self.connection
  
imports: from collections import OrderedDict
  import duckdb
  import pandas
  from duckdb import DuckDBPyConnection
  from mindsdb_sql import parse_sql
  from mindsdb_sql.parser.ast.base import ASTNode
  from mindsdb_sql.render.sqlalchemy_render import SqlalchemyRender
  from mindsdb.integrations.libs.base import DatabaseHandler
  from mindsdb.integrations.libs.const import HANDLER_CONNECTION_ARG_TYPE
  from mindsdb.integrations.libs.response import RESPONSE_TYPE
  from mindsdb.integrations.libs.response import HandlerResponse
  from mindsdb.integrations.libs.response import HandlerStatusResponse
  from mindsdb.utilities import log
label_desc: Use image node_id 3 for calling the DuckDBHandler obj's underlying member method code with example usage: obj.connect() and returns: self, self