def possible_frobenius_trace_range(field):
    """
    Return the interval in which the trace of the Frobenius endomorphism
    must reside.

    This is the naive estimation: a curve has at least one point (at infinity),
    and at most @f$ 2q + 1 @f$ points, where @f$ q @f$ is the field size.

    @return    The interval that must contain the trace of the Frobenius
               endomorphism.
    """
    return range(-field.size(), field.size() + 1)
