class_docstr: PostgreSQL Database class.
docstr: Connect to a Postgres database.
code: def connect(self):
      """Connect to a Postgres database."""
      if self.conn is None:
          try:
              self.conn = psycopg2.connect(
                  host=self.host,
                  user=self.username,
                  password=self.password,
                  port=self.port,
                  dbname=self.dbname,
              )
          except psycopg2.DatabaseError as e:
              LOGGER.error(e)
              raise e
          finally:
              LOGGER.info("Connection opened successfully.")
  
file_path: psycopg2-tutorial/psycopg2_tutorial/db.py
imports: from .log import LOGGER
  import psycopg2
  from psycopg2.extras import DictCursor
label_desc: Use image node_id 2 for calling the Database obj's underlying member method code with example usage: obj.connect() without return types