def get_default_value_for_type(t: GenericType) -> Any:
    """Get the default value of the var.

    Args:
        t: The type of the var.

    Returns:
        The default value of the var, if it has one, else None.

    Raises:
        ImportError: If the var is a dataframe and pandas is not installed.
    """
    if is_optional(t):
        return None

    origin = get_origin(t) if is_generic_alias(t) else t
    if origin is Literal:
        args = get_args(t)
        return args[0] if args else None
    if safe_issubclass(origin, TYPES_THAT_HAS_DEFAULT_VALUE):
        return origin()
    if safe_issubclass(origin, Mapping):
        return {}
    if is_dataframe(origin):
        try:
            import pandas as pd

            return pd.DataFrame()
        except ImportError as e:
            msg = "Please install pandas to use dataframes in your app."
            raise ImportError(msg) from e
    return None
Get the default value of the var.

    Args:
        t: The type of the var.

    Returns:
        The default value of the var, if it has one, else None.

    Raises:
        ImportError: If the var is a dataframe and pandas is not installed.
    
reflex/utils/types.py