How to make a blanket `impl MyTrait for T: FunctorMut<'a, A>`?

[Expurple]

I tried to implement another trait (Sanitize) for all FunctorMut's where the item implements Sanitize. But when I try to do this:

use fmap::FunctorMut;

/// The Sanitize trait generalises types that are to be sanitized.
pub trait Sanitize {
    /// Call this associated method when sanitizing.
    fn sanitize(&mut self);
}

/// A blanket impl that allows sanitizing values inside of common data structures like [Option] and [Vec].
///
/// ## Example
///
/// ```
/// use sanitizer::Sanitize;
///
/// #[derive(Debug, PartialEq)]
/// struct MyValue(i32);
///
/// impl Sanitize for MyValue {
///     /// If the inner value is `0`, change it to `1`.
///     fn sanitize(&mut self) {
///         if self.0 == 0 {
///             self.0 = 1;
///         }
///     }
/// }
///
/// let mut wrapped_value = Some(MyValue(0));
/// wrapped_value.sanitize();
/// assert_eq!(wrapped_value, Some(MyValue(1)));
/// ```
impl<'a, A, T> Sanitize for T
where
    A: 'a,
    T: FunctorMut<'a, A>,
    T::Inner: Sanitize,
{
    fn sanitize(&mut self) {
        self.fmap_mut(Sanitize::sanitize)
    }
}

I get this error:

error[E0207]: the type parameter `A` is not constrained by the impl trait, self type, or predicates

and I don't know how to proceed.

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