old_contents: import logging
  from .main import special_command, RAW_QUERY, PARSED_QUERY
  
  log = logging.getLogger(__name__)
  
  @special_command('\\dt', '\\dt', 'List or describe tables.', arg_type=PARSED_QUERY, case_sensitive=True)
  def list_tables(cur, arg=None, arg_type=PARSED_QUERY):
      if arg:
          query = 'SHOW FIELDS FROM {0}'.format(arg)
      else:
          query = 'SHOW TABLES'
      log.debug(query)
      cur.execute(query)
      if cur.description:
          headers = [x[0] for x in cur.description]
          return [(None, cur, headers, '')]
      else:
          return [(None, None, None, '')]
  
  @special_command('\\l', '\\l', 'List databases.', arg_type=RAW_QUERY, case_sensitive=True)
  def list_databases(cur, **_):
      query = 'SHOW DATABASES'
      log.debug(query)
      cur.execute(query)
      if cur.description:
          headers = [x[0] for x in cur.description]
          return [(None, cur, headers, '')]
      else:
          return [(None, None, None, '')]
  
  
new_contents: import logging
  from .main import special_command, RAW_QUERY, PARSED_QUERY
  
  log = logging.getLogger(__name__)
  
  @special_command('\\dt', '\\dt [table]', 'List or describe tables.', arg_type=PARSED_QUERY, case_sensitive=True)
  def list_tables(cur, arg=None, arg_type=PARSED_QUERY):
      if arg:
          query = 'SHOW FIELDS FROM {0}'.format(arg)
      else:
          query = 'SHOW TABLES'
      log.debug(query)
      cur.execute(query)
      if cur.description:
          headers = [x[0] for x in cur.description]
          return [(None, cur, headers, '')]
      else:
          return [(None, None, None, '')]
  
  @special_command('\\l', '\\l', 'List databases.', arg_type=RAW_QUERY, case_sensitive=True)
  def list_databases(cur, **_):
      query = 'SHOW DATABASES'
      log.debug(query)
      cur.execute(query)
      if cur.description:
          headers = [x[0] for x in cur.description]
          return [(None, cur, headers, '')]
      else:
          return [(None, None, None, '')]
  
  
subject: Change \dt syntax to add an optional table name.