Error message when creating invalid interval

[carlos-adir]

When trying to create an interval when end <= start, we receive the error message:

def __init__(
        self, start: Real, end: Real, left: bool = True, right: bool = True
    ):
        start = To.real(start)
        end = To.real(end)
        if end <= start:
>           raise ValueError(
                "Received interval [{start}, {end}], but {end} <= {start}"
            )
E           ValueError: Received interval [{start}, {end}], but {end} <= {start}

It seems missing a f for format strings