Querier in Cw20Contract in helpers.rs

Help please.

I am trying to use the Cw20Contract to Query things about a CW20 contract. All the querying functions take a Querier argument. But I don't know where to get the querier object from.

If I try and so this (e.g.):

let _test = cw20.is_mintable(&deps.querier);

I get this error:

error[E0277]: the trait bound `QuerierWrapper<'_>: Querier` is not satisfied
   --> src/contract.rs:132:38
    |
132 |         let _test = cw20.is_mintable(&deps.querier);
    |                          ----------- ^^^^^^^^^^^^^ the trait `Querier` is not implemented for `QuerierWrapper<'_>`
    |                          |
    |                          required by a bound introduced by this call
    |
    = help: the trait `Querier` is implemented for `MockQuerier<C>`
note: required by a bound in `Cw20Contract::is_mintable`
   --> /Users/diarmidcampbell/.cargo/registry/src/github.com-1ecc6299db9ec823/cw20-0.13.1/src/helpers.rs:118:27
    |
118 |     pub fn is_mintable<Q: Querier, CQ: CustomQuery>(&self, querier: &Q) -> bool {
    |                           ^^^^^^^ required by this bound in `Cw20Contract::is_mintable`